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There are several ways to use a tape machine on Linux, mainlythrough software such as Amanda and Tar.

Amanda provides the ability to provide remote centralizedbackup by setting the client side and the server side forremotecentralized storage. Tar is mostly used in a single machineenvironment to write data directly to a tape backup. For asingle node backup, simply use the Tar command for backup andrecovery.

The installation

For the current HP dat24/40 series of external SCSI tapemachines, all have automatic rollback functions. Take itoutside the SCSI bus and restart the server. After reboot, theexecution of the dmesgwill allowyou to see the new tapemachinedevice called /dev/st0.

Series: queue ef0d7a14, I/O limit of 4095 MB (mask 0 XFFFFFFFF)audit subsystem ver 0. 1 the initialized (scsi0: A: 3) : 10.000MB/s transfers (10.000 MHz, offset 15) Vendor: HP Model: C1537ARev: L805 Type: Sequential - Access ANSI SCSI revision: 02series: queue ef0e4614, I/O limit of 4095 MB (mask 0 XFFFFFFFF)Attached SCSI tape st0 at scsi0, channel 0, 3, id lun 0The tape operation

After loading the tape, you can do the following:

Rewind the tape to the starting position

Mt - f/dev/st0 rewind

Erase, erase the contents of the tape

Mt - f/dev/st0 erase

Note: erase work very slowly, and has damage to the tape, itis best not to perform, whenwriting data, can continue to writedata and cover the original data, and do not need to erase theaction. The new tape can be used immediately after it has beenopened, and it does not need to be erased.

Take the tape, roll the tape to the original position and thenpop up from the tape machine

Mt - f/dev/st0 offline

Data manipulation

The basic operations are as follows:

Column directory operations tar TVF/dev/st0

If there is no file on the tape, then the directorywill reportthe error, which has no relation and does not affect the useof the tape.

Root @ dev131 / root # tar TVF/dev/st0tar: / dev/st0: alwaysread: Input/output errortar:At the beginning of tape, quittingnowtar: the Error is not recoverable, exiting now root@dev131

/ root #

Write the data action tar CVF/dev/st0< to write the file name >There are two ways to write data: don't package it directly intothe file and package it to write the file. Each has itsadvantages and disadvantages. The method of not packagingdirectly into the file looks inefficient and complex, but canimprove the survival rate of the data. The tape is a linearstorage device, and all data is written next to the order. Whena point of tape is damaged, the rest of the tape can still beread, and the files can be read. If the method is packaged andcompressed, only one file is stored on the tape. Anywhere whenthe tape has malfunctioned can' t read, then the compressed filewill be lack of some details, even if it is a bit error, willalso result in CRC error can't extract the compressed filereport. So, if you're storing a lot of data, write it directly.If it is access to a small file, it is best to package it andadd a time tag to the file name.

For example, to write/root/test1.tar.gz to the tape andoverwrite the tape:

Tar CVF/dev/st0 test1. tar.gz

The speed of the tape is slower, for not a large file backup,wait a few seconds, and the write can be done. Using theparameter CVF will overwrite the existing files on this.Then list the files on the tape:

[root @dev131 / root] # tar TVF/dev/st0-rw-rw- r - root/root320 2006-1201. Tar.gz [root @dev131 / root] #

You can see the data written successfully.

Note: this command will only be written when the tape isentirely new, and the original data will be overridden on thesecond execution. In addition, using the tar command backup,the required backup file volume must be less than the capacityof a single disk of tape, which means a file cannot span twosets of tape. If this is the case, you can' t use the tar commandbackup, and you need to change the other backup programs to doso.

Continue to write the data tar RVF/dev/st0 < to write the filen ame >

Tape storage is a linear storage, and all data is written inturn. To not overwrite the contents of the front, use the RVFparameter to write the content when writing.

Tar RVF/dev/st0 test2. tar.gz

Once again, the RVF continues to write to other files:Tar RVF/dev/st0 test3. tar.gz

When the write is complete, check what files are on the tape:Root@dev131 /root#tar TVF/dev/st0-rw-r-r-320 root/root2006-12-01 09:29:02 test1. Tar. Gz -rw-r- r- 320 root/root

2006-12-01 09:44:19 test2. Tar. Gz -rw-r- r- 320 root/root2006-12-01 09:30:14 test3. Tar. Gz root @ dev131 / root #As you can see, the newly written files and the original filesare stored on the tape.

The linear storage feature of the tape makes it possible towrite the same file twice. For example, now the test3 file hasa file size change that is written to the tape again:Tar RVF/dev/st0 test3. tar.gz

Looking at the list of files, you can see the following fileson the tape:

Root@dev131 /root#tar TVF/dev/st0-rw-r-r-320 root/root2006-12-01 09:29:02 test1. Tar. Gz -rw-r- r- 320 root/root2006-12-01 09:30:14 test2. Tar. Gz -rw-r- r- 320 root/root2006-12-01 09:44:19 test3. Tar. Gz-rw-r-r-67085 root/root2006-12-01 09:44:19 test3. Tar. Gz root @ dev131 / root #Here you can see that there are two file names of the same nameon the tape. The two backup sizes of this file can be the sameor not the same.

Note: on tape if the file is written to the same times, therecovery time will be more troublesome, need to tape to documentstorage place, and then read the tape files stored in thecurrent position, more complicated to operate, speed is alsoslow. So it is not recommended to write the same file name ona tape. Before backing up, it is best to add a time tag to the

file name of the backup file so that you can find the backup.For example, the file name to be backed up istest-20061201-0930. tar.gz and test-20061201-0945.tar.gz,which is written to a tape. This makes it easier and faster toaccess and access operations when performing backup and restoreoperations.

Read the data tar XVF/dev/st0 < to read the file name >Before reading the data, check the content on the tape to getthe file name to be restored. For example, see the followingresults:

Root@dev131 /root#tar TVF/dev/st0-rw-r-r-320 root/root2006-12-01 09:29:02 test1. Tar. Gz -rw-r- r- 320 root/root2006-12-01 09:30:14 test2. Tar. Gz -rw-r- r- 320 root/root2006-12-01 09:44:19 test3. Tar. Gz root @ dev131 / root #Now restore the test3.tar.gz file, and execute the followingcommand:

Tar XVF/dev/st0 test3. tar.gz

After reading the data.

[root @dev131] # tar XVF/dev/st0 test3. tar.gz

You can then find the files that are read from the tape in thecurrent path:

[root @dev131 ~] # ls-l test3.tar.gz-rw-r -- r -- 1 root root

320 Dec 1 11: 12 test3. tar.gz

This completes the restore operation.

Using the tar command described above, you can use theTVF/CVF/RVF/XVF parameter to implement the read and writeoperation of the tape. The automatic backup can be implementedusing pre-written copy data scripts, combined with the tapemachine operation command, and placed in /etc/crontab.