tar file size limit

Generally, tar can't handle files larger than 2GB. I suggest using an alternative to tar, 'star'. A more comprehensive answer is available here:


--->
The quick answer is: 2^63-1 for the archive, 68'719'476'735 (8^12-1)
bytes for each file, if your environment permits that.

as I understand your question, you want to know if you can produce tar
files that are biger than 2 GBytes (and how big you can really make
them). The answer to this question depends on a few simple parameters:

1) Does your operating system support large files?
2) What version of tar are you using?
3) What is the underlying file system?

You can answer question 1) for yourself by verifying that your kernel
supports 64bit file descriptors. For Linux this is the case for
several years now. A quick look in /usr/include/sys/features.h will
tell you, if there is any line containing 'FILE_OFFSET_BITS'. If there
is, your OS very very probably has support for large files.

For Solaris, just check whether 'man largefile' works, or try 'getconf
-a|grep LARGEFILE'. If it works, then you have support for large files
in the operating system. Again, support for large files has been there
for several years.

For other operating systems, try "man -k large file', and see what you
get -- I'll be gladly providing help if you need to ask for
clarification to this answer. Something like "cd /usr/include; grep
'FILE_OFFSET_BITS' * */*" should tell you quickly if there is standard
large file support.

2) What version of tar are you using? This is important. Obviously,
older tar programs won't be able to handle files or archives that are
larger than 2^31-1 bytes (2.1 Gigabytes). Try running 'tar --version'.
If the first line indicates you are using gnu tar, then any version
newer than 1.12.64 will in principle be able to provide you with large
files. Try to run this command: "strings `which tar`|grep 64", and you
should see some lines saying lseek64, creat64, fopen64. If yes, your
tar contains support for large files.

If your tar program does not contain support for large files (most
really do, but maybe you are working on a machine older than 1998?),
you can download the newest gnu tar from ftp://ftp.gnu.org/pub/gnu/tar
and compile it for yourself.

The size of files you put into a tar archive (not the archive itself)
is limited to 11 octal digits, the max. size of a single file is thus
ca. 68 GBytes.

3) Given that both your operating system (and C library), and tar
application support large files, the only really limiting factor is
the file system that you try to create the file in. The theoretical
limit for the tar archive size is 2^63-1 (9'223'372 Terabytes), but
you will reach more practical limits (disk or tape size) much quicker.
Also take into consideration what the file system is. DOS FAT 12
filesystems don't allow files as big as the Linux EXT2, or Sun UFS
file systems.

If you need more precise data (for a specific file system type, or for
the OS, etc.) please do not hesitate to ask for clarification.

I hope my answer is helpful to you,
Rajeev

Amazon EC2 Instance Types

Amazon EC2 Instance Types

Amazon Elastic Compute Cloud (Amazon EC2) provides the flexibility to choose from a number of different instance types to meet your computing needs. Each instance provides a predictable amount of dedicated compute capacity and is charged per instance-hour consumed.
Available Instance Types
Standard Instances

Instances of this family are well suited for most applications.

Small Instance – default*

1.7 GB memory
1 EC2 Compute Unit (1 virtual core with 1 EC2 Compute Unit)
160 GB instance storage
32-bit platform
I/O Performance: Moderate
API name: m1.small

Large Instance

7.5 GB memory
4 EC2 Compute Units (2 virtual cores with 2 EC2 Compute Units each)
850 GB instance storage
64-bit platform
I/O Performance: High
API name: m1.large

Extra Large Instance

15 GB memory
8 EC2 Compute Units (4 virtual cores with 2 EC2 Compute Units each)
1,690 GB instance storage
64-bit platform
I/O Performance: High
API name: m1.xlarge
Micro Instances

Instances of this family provide a small amount of consistent CPU resources and allow you to burst CPU capacity when additional cycles are available. They are well suited for lower throughput applications and web sites that consume significant compute cycles periodically.

Micro Instance

613 MB memory
Up to 2 EC2 Compute Units (for short periodic bursts)
EBS storage only
32-bit or 64-bit platform
I/O Performance: Low
API name: t1.micro
High-Memory Instances

Instances of this family offer large memory sizes for high throughput applications, including database and memory caching applications.

High-Memory Extra Large Instance

17.1 GB of memory
6.5 EC2 Compute Units (2 virtual cores with 3.25 EC2 Compute Units each)
420 GB of instance storage
64-bit platform
I/O Performance: Moderate
API name: m2.xlarge

High-Memory Double Extra Large Instance

34.2 GB of memory
13 EC2 Compute Units (4 virtual cores with 3.25 EC2 Compute Units each)
850 GB of instance storage
64-bit platform
I/O Performance: High
API name: m2.2xlarge

High-Memory Quadruple Extra Large Instance

68.4 GB of memory
26 EC2 Compute Units (8 virtual cores with 3.25 EC2 Compute Units each)
1690 GB of instance storage
64-bit platform
I/O Performance: High
API name: m2.4xlarge
High-CPU Instances

Instances of this family have proportionally more CPU resources than memory (RAM) and are well suited for compute-intensive applications.

High-CPU Medium Instance

1.7 GB of memory
5 EC2 Compute Units (2 virtual cores with 2.5 EC2 Compute Units each)
350 GB of instance storage
32-bit platform
I/O Performance: Moderate
API name: c1.medium

High-CPU Extra Large Instance

7 GB of memory
20 EC2 Compute Units (8 virtual cores with 2.5 EC2 Compute Units each)
1690 GB of instance storage
64-bit platform
I/O Performance: High
API name: c1.xlarge
Cluster Compute Instances

Instances of this family provide proportionally high CPU resources with increased network performance and are well suited for High Performance Compute (HPC) applications and other demanding network-bound applications. Learn more about use of this instance type for HPC applications.

Cluster Compute Quadruple Extra Large Instance

23 GB of memory
33.5 EC2 Compute Units (2 x Intel Xeon X5570, quad-core “Nehalem” architecture)
1690 GB of instance storage
64-bit platform
I/O Performance: Very High (10 Gigabit Ethernet)
API name: cc1.4xlarge
Cluster GPU Instances

Instances of this family provide general-purpose graphics processing units (GPUs) with proportionally high CPU and increased network performance for applications benefitting from highly parallelized processing, including HPC, rendering and media processing applications. While Cluster Compute Instances provide the ability to create clusters of instances connected by a low latency, high throughput network, Cluster GPU Instances provide an additional option for applications that can benefit from the efficiency gains of the parallel computing power of GPUs over what can be achieved with traditional processors. Learn more about use of this instance type for HPC applications.

Cluster GPU Quadruple Extra Large Instance

22 GB of memory
33.5 EC2 Compute Units (2 x Intel Xeon X5570, quad-core “Nehalem” architecture)
2 x NVIDIA Tesla “Fermi” M2050 GPUs
1690 GB of instance storage
64-bit platform
I/O Performance: Very High (10 Gigabit Ethernet)
API name: cg1.4xlarge
Selecting Instance Types

Amazon EC2 instances are grouped into six families: Standard, Micro, High-Memory, High-CPU, Cluster Compute, and Cluster GPU.

Standard Instances have memory to CPU ratios suitable for most general purpose applications; High-Memory instances offer larger memory sizes for high throughput applications, including database and memory caching applications; and High-CPU instances have proportionally more CPU resources than memory (RAM) and are well suited for compute-intensive applications.

Micro instances provide a small amount of consistent CPU resources and allow you to burst CPU capacity when additional cycles are available. They are well suited for lower throughput applications and web sites that consume significant compute cycles periodically. At steady state, Micro instances receive a fraction of the compute resources that Small instances do. Therefore, if your application has compute-intensive or steady state needs we recommend using a Small instance (or larger, depending on your needs). However, Micro instances can periodically burst up to 2 ECUs (for short periods of time). This is double the number of ECUs available from a Standard Small instance. Therefore, if you have a relatively low throughput application or web site with an occasional need to consume significant compute cycles, we recommend using Micro instances.

Cluster Compute instances provide a very large amount of CPU coupled with increased network performance making them well suited for High Performance Compute (HPC) applications and other demanding network-bound applications.

Cluster GPU instances provide general-purpose graphics processing units (GPUs) with proportionally high CPU and increased network performance making them well suited for applications benefitting from highly parallelized processing, including HPC, rendering and media processing applications.

When choosing instance types, you should consider the characteristics of your application with regards to resource utilization and select the optimal instance family and size. One of the advantages of EC2 is that you pay by the instance hour, which makes it convenient and inexpensive to test the performance of your application on different instance families and types. One good way to determine the most appropriate instance family and instance type is to launch test instances and benchmark your application.
Measuring Compute Resources

Transitioning to a utility computing model fundamentally changes how developers have been trained to think about CPU resources. Instead of purchasing or leasing a particular processor to use for several months or years, you are renting capacity by the hour. Because Amazon EC2 is built on commodity hardware, over time there may be several different types of physical hardware underlying EC2 instances. Our goal is to provide a consistent amount of CPU capacity no matter what the actual underlying hardware.

Amazon EC2 uses a variety of measures to provide each instance with a consistent and predictable amount of CPU capacity. In order to make it easy for developers to compare CPU capacity between different instance types, we have defined an Amazon EC2 Compute Unit. The amount of CPU that is allocated to a particular instance is expressed in terms of these EC2 Compute Units. We use several benchmarks and tests to manage the consistency and predictability of the performance of an EC2 Compute Unit. One EC2 Compute Unit provides the equivalent CPU capacity of a 1.0-1.2 GHz 2007 Opteron or 2007 Xeon processor. This is also the equivalent to an early-2006 1.7 GHz Xeon processor referenced in our original documentation. Over time, we may add or substitute measures that go into the definition of an EC2 Compute Unit, if we find metrics that will give you a clearer picture of compute capacity.

To find out which instance will work best for your application, the best thing to do is to launch an instance and benchmark your own application. One of the advantages of EC2 is that you pay by the hour which makes it convenient and inexpensive to test the performance of your application on different instance types.
I/O Performance

Amazon EC2 provides virtualized server instances. While some resources like CPU, memory and instance storage are dedicated to a particular instance, other resources like the network and the disk subsystem are shared among instances. If each instance on a physical host tries to use as much of one of these shared resources as possible, each will receive an equal share of that resource. However, when a resource is under-utilized you will often be able to consume a higher share of that resource while it is available.

The different instance types will provide higher or lower minimum performance from the shared resources depending on their size. Each of the instance types has an I/O performance indicator (low, moderate, or high). Instance types with high I/O performance have a larger allocation of shared resources. Allocating larger share of shared resources also reduces the variance of I/O performance. For many applications, low or moderate I/O performance is more than enough. However, for those applications requiring greater or more consistent I/O performance, you may want to consider instances with high I/O performance.

Cluster Compute and Cluster GPU instances have very high I/O performance using 10 Gigabit Ethernet for high network throughput and reduced network latencies within clusters.

In addition, you can use Amazon EBS to get improved storage I/O performance for disk bound applications.



*The Small Instance type is equivalent to the original Amazon EC2 instance type that has been available since Amazon EC2 launched. This instance type is currently the default for all customers. To use other instance types, customers must specifically request them via the RunInstances API.

How to disable SSH host key checking

Remote login using the SSH protocol is a frequent activity in today's internet world. With the SSH protocol, the onus is on the SSH client to verify the identity of the host to which it is connecting. The host identify is established by its SSH host key. Typically, the host key is auto-created during initial SSH installation setup.

By default, the SSH client verifies the host key against a local file containing known, rustworthy machines. This provides protection against possible Man-In-The-Middle attacks. However, there are situations in which you want to bypass this verification step. This article explains how to disable host key checking using OpenSSH, a popular Free and Open-Source implementation of SSH.

When you login to a remote host for the first time, the remote host's host key is most likely unknown to the SSH client. The default behavior is to ask the user to confirm the fingerprint of the host key.

$ ssh Rajeev@192.168.0.100
The authenticity of host '192.168.0.100 (192.168.0.100)' can't be established.
RSA key fingerprint is 3f:1b:f4:bd:c5:aa:c1:1f:bf:4e:2e:cf:53:fa:d8:59.
Are you sure you want to continue connecting (yes/no)?


If your answer is yes, the SSH client continues login, and stores the host key locally in the file ~/.ssh/known_hosts. You only need to validate the host key the first time around: in subsequent logins, you will not be prompted to confirm it again.

Yet, from time to time, when you try to remote login to the same host from the same origin, you may be refused with the following warning message:

$ ssh Rajeev@192.168.0.100
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
3f:1b:f4:bd:c5:aa:c1:1f:bf:4e:2e:cf:53:fa:d8:59.
Please contact your system administrator.
Add correct host key in /home/peter/.ssh/known_hosts to get rid of this message.
Offending key in /home/rajeev/.ssh/known_hosts:3
RSA host key for 192.168.0.100 has changed and you have requested strict checking.
Host key verification failed.$


There are multiple possible reasons why the remote host key changed. A Man-in-the-Middle attack is only one possible reason. Other possible reasons include:

* OpenSSH was re-installed on the remote host but, for whatever reason, the original host key was not restored.
* The remote host was replaced legitimately by another machine.


If you are sure that this is harmless, you can use either 1 of 2 methods below to trick openSSH to let you login. But be warned that you have become vulnerable to man-in-the-middle attacks.

The first method is to remove the remote host from the ~/.ssh/known_hosts file. Note that the warning message already tells you the line number in the known_hosts file that corresponds to the target remote host. The offending line in the above example is line 3("Offending key in /home/rajeev/.ssh/known_hosts:3")

You can use the following one liner to remove that one line (line 3) from the file.

$ sed -i 3d ~/.ssh/known_hosts


Note that with the above method, you will be prompted to confirm the host key fingerprint when you run ssh to login.

The second method uses two openSSH parameters:

* StrictHostKeyCheckin, and

* UserKnownHostsFile.


This method tricks SSH by configuring it to use an empty known_hosts file, and NOT to ask you to confirm the remote host identity key.

$ ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no rajeev@192.168.0.100
Warning: Permanently added '192.168.0.100' (RSA) to the list of known hosts.
peter@192.168.0.100's password:


The UserKnownHostsFile parameter specifies the database file to use for storing the user host keys (default is ~/.ssh/known_hosts).

The /dev/null file is a special system device file that discards anything and everything written to it, and when used as the input file, returns End Of File immediately.

By configuring the null device file as the host key database, SSH is fooled into thinking that the SSH client has never connected to any SSH server before, and so will never run into a mismatched host key.

The parameter StrictHostKeyChecking specifies if SSH will automatically add new host keys to the host key database file. By setting it to no, the host key is automatically added, without user confirmation, for all first-time connection. Because of the null key database file, all connection is viewed as the first-time for any SSH server host. Therefore, the host key is automatically added to the host key database with no user confirmation. Writing the key to the /dev/null file discards the key and reports success.

Please refer to this excellent article about host keys and key checking.

By specifying the above 2 SSH options on the command line, you can bypass host key checking for that particular SSH login. If you want to bypass host key checking on a permanent basis, you need to specify those same options in the SSH configuration file.

You can edit the global SSH configuration file (/etc/ssh/ssh_config) if you want to make the changes permanent for all users.

If you want to target a particular user, modify the user-specific SSH configuration file (~/.ssh/config). The instructions below apply to both files.

Suppose you want to bypass key checking for a particular subnet (192.168.0.0/24).

Add the following lines to the beginning of the SSH configuration file.

Host 192.168.0.*
StrictHostKeyChecking no
UserKnownHostsFile=/dev/null


Note that the configuration file should have a line like Host * followed by one or more parameter-value pairs. Host *means that it will match any host. Essentially, the parameters following Host * are the general defaults. Because the first matched value for each SSH parameter is used, you want to add the host-specific or subnet-specific parameters to the beginning of the file.

As a final word of caution, unless you know what you are doing, it is probably best to bypass key checking on a case by case basis, rather than making blanket permanent changes to the SSH configuration files.

netapp command summary

sysconfig -a : shows hardware configuration with more verbose information
sysconfig -d : shows information of the disk attached to the filer
version : shows the netapp Ontap OS version.
uptime : shows the filer uptime
dns info : this shows the dns resolvers, the no of hits and misses and other info
nis info : this shows the nis domain name, yp servers etc.
rdfile : Like "cat" in Linux, used to read contents of text files/
wrfile : Creates/Overwrites a file. Similar to "cat > filename" in Linux
aggr status : Shows the aggregate status
aggr status -r : Shows the raid configuration, reconstruction information of the disks in filer
aggr show_space : Shows the disk usage of the aggreate, WAFL reserve, overheads etc.
vol status : Shows the volume information
vol status -s : Displays the spare disks on the filer
vol status -f : Displays the failed disks on the filer
vol status -r : Shows the raid configuration, reconstruction information of the disks
df -h : Displays volume disk usage
df -i : Shows the inode counts of all the volumes
df -Ah : Shows "df" information of the aggregate
license : Displays/add/removes license on a netapp filer
maxfiles : Displays and adds more inodes to a volume
aggr create : Creates aggregate
vol create : Creates volume in an aggregate
vol offline : Offlines a volume
vol online : Onlines a volume
vol destroy : Destroys and removes an volume
vol size [+|-] : Resize a volume in netapp filer
vol options : Displays/Changes volume options in a netapp filer
qtree create : Creates qtree
qtree status : Displays the status of qtrees
quota on : Enables quota on a netapp filer
quota off : Disables quota
quota resize : Resizes quota
quota report : Reports the quota and usage
snap list : Displays all snapshots on a volume
snap create : Create snapshot
snap sched : Schedule snapshot creation
snap reserve : Display/set snapshot reserve space in volume
/etc/exports : File that manages the NFS exports
rdfile /etc/exports : Read the NFS exports file
wrfile /etc/exports : Write to NFS exports file
exportfs -a : Exports all the filesystems listed in /etc/exports
cifs setup : Setup cifs
cifs shares : Create/displays cifs shares
cifs access : Changes access of cifs shares
lun create : Creates iscsi or fcp luns on a netapp filer
lun map : Maps lun to an igroup
lun show : Show all the luns on a filer
igroup create : Creates netapp igroup
lun stats : Show lun I/O statistics
disk show : Shows all the disk on the filer
disk zero spares : Zeros the spare disks
disk_fw_update : Upgrades the disk firmware on all disks
options : Display/Set options on netapp filer
options nfs : Display/Set NFS options
options timed : Display/Set NTP options on netapp.
options autosupport : Display/Set autosupport options
options cifs : Display/Set cifs options
options tcp : Display/Set TCP options
options net : Display/Set network options
ndmpcopy : Initiates ndmpcopy
ndmpd status : Displays status of ndmpd
ndmpd killall : Terminates all the ndmpd processes.
ifconfig : Displays/Sets IP address on a network/vif interface
vif create : Creates a VIF (bonding/trunking/teaming)
vif status : Displays status of a vif
netstat : Displays network statistics
sysstat -us 1 : begins a 1 second sample of the filer's current utilization (crtl - c to end)
nfsstat : Shows nfs statistics
nfsstat -l : Displays nfs stats per client
nfs_hist : Displays nfs historgram
statit : beings/ends a performance workload sampling [-b starts / -e ends]
stats : Displays stats for every counter on netapp. Read stats man page for more info
ifstat : Displays Network interface stats
qtree stats : displays I/O stats of qtree
environment : display environment status on shelves and chassis of the filer
storage show : Shows storage component details
snapmirror intialize : Initialize a snapmirror relation
snapmirror update : Manually Update snapmirror relation
snapmirror resync : Resyns a broken snapmirror
snapmirror quiesce : Quiesces a snapmirror bond
snapmirror break : Breakes a snapmirror relation
snapmirror abort : Abort a running snapmirror
snapmirror status : Shows snapmirror status
lock status -h : Displays locks held by filer
sm_mon : Manage the locks
storage download shelf : Installs the shelf firmware
software get : Download the Netapp OS software
software install : Installs OS
download : Updates the installed OS
cf status : Displays cluster status
cf takeover : Takes over the cluster partner
cf giveback : Gives back control to the cluster partner
reboot : Reboots a filer

inetd: the Internet super server

inetd: the Internet super server



==> Understanding inetd
==> Configuring inetd


What does inetd do?


To provide services over the network, you need an application that understands your requests and can provide that service. These applications usually work behind the scenes, without any user interface and interaction. This means that they are not visible in the normal work environment.

They are called daemons or network daemons. A daemon "listens" on a specific port for incoming requests. When a request arrives, the daemon "wakes up" and begins to perform a specific operation.

If you want to have many services available on your machine, you need to run a daemon for each service. These daemons need memory, take up space in the process table, and so on. For frequently used services, standalone daemons make sense. For services that receive few requests, they're a waste of resources.

To help you optimize your resources, there is a super server that can be configured to listen in on a list of ports and invoke the specific application the moment a request for the application arrives. This daemon is inetd. Most of the network daemons offer you the option to set them to run as stand-alone applications, or to be invoked by inetd on demand. Although the setup with inetd saves resources in the time the service is not used, it creates a delay for the client. The daemon for this service has to be loaded and probably has to initialize itself before it's ready to serve the request. You might think about which services you want to run as stand-alone applications and which ones you want to be called by inetd.

HTTP servers such as Apache are likely to be run as stand-alone services. Apache needs a relatively long load time, and you don't want your customers waiting too long while your Web site loads. Apache is highly optimized to run in stand-alone mode, so you probably don't want it to be spawned by inetd. A service such as in.telnetd, which enables logins from other machines, doesn't need much time to load. It makes a good candidate for being invoked by the super server.

You should be sure that you need inetd before you set it up. A client machine that primarily acts as a workstation has no need to run inetd, because the client machine is not meant to provide any services for the network. You probably don't need inetd for home machines. It's basically a question of security. Using inetd on machines on which you really don't need it may reveal possible entry points for crackers. Running inetd-enabled services such as telnet and rlogin can be used to exploit your machine. This doesn't mean that those services are generally insecure, but they may be a first source of information for potential crackers trying to enter your system.

During the installation, SuSE asks whether inetd should be started. The referring variable in /etc/rc.config is START_INETD. If it is set to yes, inetd will start at system boot time.

Configuring inetd


The inetd daemon reads several files in /etc when it's executed. The main configuration file is /etc/inetd.conf. It specifies which daemon should be started for which service.

The other files it reads are shared with other daemons and contain more general information about Internet services.


* /etc/services
This file maps port numbers to service names. Most of the port numbers below 1024 are assigned to special services (specified in RFC 1340). These assignments are reflected in this file. Every time you refer to a service by its name (as opposed to its port number), this name will be looked up in /etc/services and the referring port number will be used to process your request.
* /etc/rpc
Just like /etc/services, but with RPC (Remote Procedure Call), services are mapped to names.
* /etc/protocols
Another map. Here, protocols are specified and mapped to the numbers the kernel uses to distinguish between the different TCP/IP protocols.


Usually none of these files needs to be edited. The only candidate for changes is /etc/services. If you run some special daemon on your system (such as a database engine), you may want to add the port number of this service to this list.

The inetd daemon needs these files because in its own configuration file /etc/inetd.conf, these names are used to specify which daemon should be started to serve each service. Each line defines one service. Comment lines (starting with a hash sign -- #) and empty lines are ignored. The definition lines have seven fields, which must all contain legal values:


* service name
The name of a valid service in the file /etc/services. For internal services (discussed in the next chapter), the service name must be the official name of the service (that is, the first entry in /etc/services). When used to specify a Sun-RPC based service, this field is a valid RPC service name like listed in the file /etc/rpc. The part on the right of the slash (/) is the RPC version number. This can simply be a single numeric argument or a range of versions. A range is bounded by the lowest value to the highest value (for example, rusers/1-3).
* socket type
These should be one of the keywords stream, dgram, raw, rdm, or seqpacket, depending on whether the socket is a stream, datagram, raw, reliably delivered message, or sequenced packet socket.
* protocol
The protocol must be a valid protocol as listed in /etc/protocols. Examples might be tcp or udp. RPC-based services are specified with the rpc/tcp or rpc/udp service type.
* wait/nowait.max
The wait/nowait entry is applicable to datagram sockets only (other sockets should have a nowait entry in this space). If a datagram server connects to its peer, freeing the socket so that inetd can receive further messages on the socket, it is said to be a multithreaded server and should use the nowait entry. For datagram servers that process all incoming datagrams on a socket and eventually time out, the server is said to be single-threaded and should use a wait entry. Comsat(8) and talkd(8) are both examples of the latter type of datagram server. The optional max suffix (separated from wait or nowait by a period) specifies the maximum number of server instances that may be spawned from inetd within an interval of 60 seconds. When omitted, it defaults to 40.
* user.group
This entry should contain the user name of the user as whom the server should run. This allows for servers to be given less permission than root. An optional group name can be specified by appending a dot to the user name followed by the group name. This allows for servers to run with a different (primary) group id than specified in the password file. If a group is specified and user is not root, the supplementary groups associated with that user will still be set.
* server program
The server-program entry should contain the pathname of the program that is to be executed by inetd when a request is found on its socket. If inetd provides this service internally, this entry should be internal.
* server program arguments
This is the place to give arguments to the daemon. Note that they are starting with argv[0], which is the name of the program. If the service is provided internally, the keyword internal should take the place of this entry.


The inetd daemon provides several trivial services internally by use of routines within itself. These services are echo, discard, chargen (character generator), daytime (human readable time), and time (machine readable time, in the form of the number of seconds since midnight, January 1, 1900).

XREF These services are discussed more extensively in Chapter 12 .


Some examples can show you how it works. To enable telnet into the machine, you will need a line like this in /etc/inetd.conf:



telnet stream tcp nowait root /usr/sbin/in.telnetd in.telnetd



Telnet is the name of the service, it uses a stream socket and TCP protocol, and because it's a TCP service, you can specify it as nowait. The user ID the daemon should run with is root. The last two arguments give the path and name of the actual server application and its arguments.

You always have to give the program name here, because most daemons require it to get a argv[0].

An example for a datagram-based service is talk:



talk dgram udp wait root /usr/sbin/in.talkd in.talkd



You see the differences. Rather than stream you use dgram to specify a datagram type of service. The socket type is set to udp and inetd has to wait until the daemon exits before waiting for new connections.

Now if you look into the preinstalled /etc/inetd.conf file, you will notice that almost all services are using /usr/sbin/tcpd as a daemon for the service, and give the actual service daemon on the command line for tcpd. This is done to increase network security. The tcpd daemon acts as a wrapper and provides lists of hosts who are allowed to use this service. For the moment, think about tcpd as an in-between step that starts the daemon after checking whether the person requesting the service is actually allowed to do this. The SuSE default configuration allows everybody to connect to any port.

how Netapp Snapvault works

Netapp Snapvault guide
Compiled by Rajeev

Netapp SnapVault is a heterogeneous disk-to-disk backup solution for Netapp filers and heterogeneous OS systems (Windows, Linux , Solaris, HPUX and AIX). Basically, Snapvault uses Snapshot technology to store online backups. In event of data loss or corruption on a filer, the backup data can be restored from the SnapVault filer with less downtime. It has significant advantages over traditional tape backups, like
• Media cost savings
• Reduce backup windows versus traditional tape-based backup
• No backup/recovery failures due to media errors
• Simple and Fast recovery of corrupted or destroyed data

Snapvault consists of major two entities – snapvault clients and a snapvault storage server. A snapvault client (Netapp filers and unix/windows servers) is the system whose data should be backed-up. The SnapVault server is a Netapp filer – which gets the data from clients and backs up data.

Snapvault supports two types of backup infrastructure:
1. Netapp to Netapp backups
2. Server to Netapp backups

For Server to Netapp Snapvault, we need to install Open System Snapvault client software provided by Netapp, on the servers. Using the snapvault agent software, the Snapvault server can pull and backup data on to the backup qtrees. SnapVault protects data on a client system by maintaining a number of read-only versions (snapshots) of that data on a SnapVault filer. The replicated data on the snapvault server system can be accessed via NFS or CIFS. The client systems can restore entire directories or single files directly from the snapvault filer. Snapvault requires primary and secondary license.

How snapvault works?

When snapvault is setup, initially a complete copy of the data set is pulled across the network to the SnapVault filer. This initial or baseline, transfer may take some time to complete, because it is duplicating the entire source data set on the server – much like a level-zero backup to tape. Each subsequent backup transfers only the data blocks that has changed since the previous backup. When the initial full backup is performed, the SnapVault filer stores the data on a qtree and creates a snapshot image of the volume for the data that is to be backed up. SnapVault creates a new Snapshot copy with every transfer, and allows retention of a large number of copies according to a schedule configured by the backup administrator. Each copy consumes an amount of disk space proportional to the differences between it and the previous copy.

Snapvault commands

Initial step to setup Snapvault backup between filers is to install snapvault license and enable snapvault on all the source and destination filers.

Source filer – filer1
filer1> license add XXXXX
filer1> options snapvault.enable on
filer1> options snapvault.access host=svfiler
Destination filer – svfiler
svfiler> license add XXXXX
svfiler> options snapvault.enable on
svfiler> options snapvault.access host=filer1

In our GeekyFacts.com tutorial, consider svfiler:/vol/demo_vault as the snapvault destination volume, where all backups are done. The source data is filer1:/vol/datasource/qtree1. As we have to manage all the backups on the destination filer (svfiler) using snapvault – manually disable scheduled snapshots on the destination volumes. The snapshots will be managed by Snapvault. Disabling Netapp scheduled snapshots, with below command.
svfiler> snap sched demo_vault 0 0 0

Creating Initial backup: Initiate the initial baseline data transfer (the first full backup) of the data from source to destination before scheduling snapvault backups. On the destination filer execute the below commands to initiate the base-line transfer. The time taken to complete depends upon the size of data on the source qtree and the network bandwidth. Check “snapvault status” on source/destination filers for monitoring the base-line transfer progress.
svfiler> snapvault start -S filer1:/vol/datasource/qtree1 svfiler:/vol/demo_vault/qtree1

Creating backup schedules: Once the initial base-line transfer is completed, snapvault schedules have to be created for incremental backups. The retention period of the backup depends on the schedule created. The snapshot name should be prefixed with “sv_”. The schedule is in the form of “[@][@]”.

On source filer:

For example, let us create the schedules on source as below - 2 hourly, 2 daily and 2 weekly snapvault . These snapshot copies on the source enables administrators to recover directly from source filer without accessing any copies on the destination. This enables more rapid restores. However, it is not necessary to retain a large number of copies on the primary; higher retention levels are configured on the secondary. The commands below shows how to create hourly, daily & weekly snapvault snapshots.
filer1> snapvault snap sched datasource sv_hourly 2@0-22
filer1> snapvault snap sched datasource sv_daily 2@23
filer1> snapvault snap sched datasource sv_weekly 2@21@sun
On snapvault filer:

Based on the retention period of the backups you need, the snapvault schedules on the destination should be done. Here, the sv_hourly schedule checks all source qtrees once per hour for a new snapshot copy called sv_hourly.0. If it finds such a copy, it updates the SnapVault qtrees with new data from the primary and then takes a Snapshot copy on the destination volume, called sv_hourly.0. If you don’t use the -x option, the secondary does not contact the primary and transfer the Snapshot copy. It just creates a snapshot copy of the destination volume.
svfiler> snapvault snap sched -x demo_vault sv_hourly 6@0-22
svfiler> snapvault snap sched -x demo_vault sv_daily 14@23@sun-fri
svfiler> snapvault snap sched -x demo_vault sv_weekly 6@23@sun

To check the snapvault status, use the command "snapvault status" either on source or destination filer. And to see the backups, do a "snap list" on the destination volume - that will give you all the backup copies, time of creation etc.

Restoring data : Restoring data is as simple as that, you have to mount the snapvault destination volume through NFS or CIFS and copy the required data from the backup snapshot.

Net App filer in Vmware

For a project I have to learn some of the specialty of an iScsi NAS. To be precise it was Net App FAS 2500 Filer. These things are very nice but a little too expensive for my personal use. But Net App offers a nice simulator of their product and the simulator is free. You just need to create an account on the Net App web site and search for the word ”simulator” or just follow this link. (http://now.netapp.com/NOW/cgi-bin/simulator). Some bloody side note: the website doesn’t work fine with safari. Just use Firefox and all works well in this case.

The other prerequirement you need is a Linux OS. I don’t want install some bloody Linux on my iMac, so I use VMware Fusion and the problem is solved. I use in this tutorial the Ubuntu 8.04 LTS Server. You might be considering now why I choose Ubuntu, the simple answer is I don’t known. Normally I use Open SUSE from Novell, but in this case I really don’t know. Strange things happen some times. Another side note I will guide you trough the installation so don’t panic if you are not an unix geek. But actually as non console junkie you should consider not to buy an EMC / IBM / … NAS ☺

Create a VMware with the normal settings 1 CPU, 10 GB HD, Nat NIC and 512MB Ram. Attach the OS iso and boot the whole batch job. Using the default settings is a nice strategy for not so experienced user. I only changed the keyboard layout to “swiss german (mac)” and check in the screen “install additional software” “ssh server” file transfer will be easy. Create an user called “geek” Then after next, next, …., next, next. The server has finished the miraculous installation. As a windows administrator the first thing I have done is enter in the console

Sudo reboot

After the restart I want to log in as root user, but the install wizard doesn’t accept the root password. After some time I decided to log in as user “geek”. Because it is only a testing environment I decided to enable root login in the console

sudo passwd root

After setting the password i started a console session on my mac shell and connected with ssh. You don’t need to do this but with an ssh session you are able to use Copy and Past with the host OS. For the poor windows user putty is a nice ssh tool. The Mac and Linux user just need to enter the following commands in the console

ssh -i root

the next thing you need to do is copying the download from the net app side “7.3.1-tarfile-v22.tar” to the VM server. I use “Cyberduck”. For windows users a nice program is winscp. The Linux guys should use the mighty shell console. By the way I createt a folder named “/netapp”. So let us open the tar file

tar xvf /netapp/7.3.1-tarfile-v22.tgz

In the readme form net app gives us a hint that the simulator uses perl. To install perl on your machine use “apt-get install perl”, actually pearl was installed so you don’t need to do it. Okay now we are ready to start installing the simulator. The strangest thing on this point was I didn’t have to deal with any problems, all worked just fine. This is a bad sign.

cd /netapp/simulator
./setup.sh

and the installation starts. Some logs from the console behind

Script version 22 (18/Sep/2007)
Where to install to? [/sim]:
Would you like to install as a cluster? [no]:
Would you like full HTML/PDF FilerView documentation to be installed [yes]:
Continue with installation? [no]: yes
Creating /sim
Unpacking sim.tgz to /sim
Configured the simulators mac address to be [00:50:56:0:6c:5]
Please ensure the simulator is not running.
Your simulator has 3 disk(s). How many more would you like to add? [0]: 10

The following disk types are available in MB:
Real (Usable)
a - 43 ( 14)
b - 62 ( 30)
c - 78 ( 45)
d - 129 ( 90)
e - 535 (450)
f – 1024 (900)

If you are unsure choose the default option a
What disk size would you like to use? [a]:
Disk adapter to put disks on? [0]:
Use DHCP on first boot? [yes]:
Ask for floppy boot? [no]:
Checking the default route…
You have a single network interface called eth0 (default route) . You will not be able to access the simulator from this Linux host. If this interface is marked DOWN in ifconfig then your simulator will crash.
Which network interface should the simulator use? [default]:
Your system has 455MB of free memory. The smallest simulator memory you should choose is 110MB. The maximum simulator memory is 415MB.
The recommended memory is 512MB.
Your original default appears to be too high. Seriously consider adjusting to below the maximum amount of 415MB.
How much memory would you like the simulator to use? [512]:
Create a new log for each session? [no]:
Overwrite the single log each time? [yes]:
Adding 10 additional disk(s).
Complete. Run /sim/runsim.sh to start the simulator.

Wow this was very easy. Nice Job Net App. In the last row there is the hint how to start the simulator so lets go.

/sim/runsim.sh

Peng, Klaap, kabumm, doing and an error appears on the console “Error ./maytag.L: No such file or directory”. F.. after some time, maybe 4 hours reading logs, traying these and that, and drinking some coffee I figured out that I need to install some libraries for AMD 64. This sounds funny but it solved my problem. This was the penalty for the easy setup.

apt-get install ia32-libs


and again try to startup. I deleted some info rows from the console log. But all questions should be present in the log below.

root@netapp:/netapp/simulator# /sim/runsim.sh
runsim.sh script version Script version 22 (18/Sep/2007)
This session is logged in /sim/sessionlogs/log

NetApp Release 7.3.1: Thu Jan 8 00:10:49 PST 2009
Copyright (c) 1992-2008 NetApp.
….
….
….
Do you want to enable IPv6? [n]: n
Do you want to configure virtual network interfaces? [n]:
Please enter the IP address for Network Interface ns0 [172.16.111.136]:
Please enter the netmask for Network Interface ns0 [255.255.255.0]:
Please enter media type for ns0 {100tx-fd, auto} [auto]:
Please enter the IP address for Network Interface ns1 []:
Would you like to continue setup through the web interface? [n]:
Please enter the name or IP address of the IPv4 default gateway [172.16.111.2]:
The administration host is given root access to the filer’s
/etc files for system administration. To allow /etc root access
to all NFS clients enter RETURN below.
Please enter the name or IP address of the administration host:
Please enter timezone [GMT]:
Where is the filer located? []:
What language will be used for multi-protocol files (Type ? for list)?:
language not set
Do you want to run DNS resolver? [n]:
Do you want to run NIS client? [n]: Setting the administrative (root) password for mynetapp …

New password:
Retype new password:
Mon May 4 20:31:11 GMT [passwd.changed:info]: passwd for user ‘root’ changed.
….
….
….
This process will enable CIFS access to the filer from a Windows(R) system.
Use "?" for help at any prompt and Ctrl-C to exit without committing changes.

Your filer is currently visible to all systems using WINS. The WINS
name server currently configured is: [ 172.16.111.2 ].

(1) Keep the current WINS configuration
(2) Change the current WINS name server address(es)
(3) Disable WINS

Selection (1-3)? [1]:
A filer can be configured for multiprotocol access, or as an NTFS-only
filer. Since multiple protocols are currently licensed on this filer,
we recommend that you configure this filer as a multiprotocol filer

(1) Multiprotocol filer
(2) NTFS-only filer

Selection (1-2)? [1]:
CIFS requires local /etc/passwd and /etc/group files and default files
will be created. The default passwd file contains entries for ‘root’,
‘pcuser’, and ‘nobody’.
Enter the password for the root user []:
Retype the password:
The default name for this CIFS server is ‘MYNETAPP’.
Would you like to change this name? [n]:
Data ONTAP CIFS services support four styles of user authentication.
Choose the one from the list below that best suits your situation.

(1) Active Directory domain authentication (Active Directory domains only)
(2) Windows NT 4 domain authentication (Windows NT or Active Directory domains)
(3) Windows Workgroup authentication using the filer’s local user accounts
(4) /etc/passwd and/or NIS/LDAP authentication

Selection (1-4)? [1]: 4
What is the name of the Workgroup? [WORKGROUP]:
CIFS – Starting SMB protocol…
Welcome to the WORKGROUP Windows(R) workgroup

CIFS local server is running.

Password:
mynetapp> Mon May 4 20:32:25 GMT [console_login_mgr:info]: root logged in from console
Mon May 4 20:32:31 GMT [nbt.nbns.registrationComplete:info]: NBT: All CIFS name registrations have completed for the local server.

mynetapp>

SO this was not so hard. Now enjoy the world class filer in your VMware



netapp

Tags: app, Filer, NAS, Net, NetApp, vmware

This entry was posted on Sunday, May 10th, 2009 at 11:07 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
2 Responses to “Net App filer in Vmware”

1.
Russell Bomilla says:
Thursday, 18, March, 2010 at 4:10 am

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2.
Abomination says:
Saturday, 10, April, 2010 at 4:55 pm

I have a problem with the part that says:
[i]You have a single network interface called eth0 (default route) . You will not be able to access the simulator from this Linux host. If this interface is marked DOWN in ifconfig then your simulator will crash.[/i]
This creates also the difficulty of connecting from the Linux host to the filer using FilerView. Have you managed to find any solutions for that?
Thanks


Rajeev

source :- http://www.dambeck.ch/2009/05/10/net-app-filer-in-vmware/