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Compression to take backup on tape drives

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John Ferro
Regular Advisor

Compression to take backup on tape drives

Hello,

I got an issue from backup admin "Could you please activate the compression on the drives, as this has direct effect to the capacity of the tape library"

My host server is ia64 hp superdome server SD64B.

Regards,
6 REPLIES
Michael Steele_2
Honored Contributor
Solution

Re: Compression to take backup on tape drives

Hi

This is a samplie ioscan. Note the different device paths like /dev/rmt/2mnb /dev/rmt/c21t4d0BESTn. Anywhere where you see BEST you see FIRMWARE TAPE DRIVE COMPRESSION. Note: the little letters at the end of each, n, b, or nothing. Double check the man pages, but 'n' is no rewind, b is Berkeley, nothing is ATT unix.

What you do is note the device that you're currently using in your script, like /dev/rmt/0mb, and find its compression counter part, //dev/rmt/c21t4d0BESTb.

Work with your backup admin re: the no rewind, rewind, etc. stuff.

# ioscan -fnC tape
Class I H/W Path Driver S/W State H/W Type Description
==================================================================
=======
tape 0 1/0/8/0/0.1.10.255.14.4.0 stape CLAIMED DEVICE HP Ultrium 2-SCSI
/dev/rmt/0m /dev/rmt/0mnb /dev/rmt/c12t4d0BESTn
/dev/rmt/0mb /dev/rmt/c12t4d0BEST /dev/rmt/c12t4d0BESTnb
/dev/rmt/0mn /dev/rmt/c12t4d0BESTb
tape 2 1/0/10/0/0.1.10.255.14.4.0 stape CLAIMED DEVICE HP Ultrium 2-SCSI
/dev/rmt/2m /dev/rmt/2mnb /dev/rmt/c21t4d0BESTn
/dev/rmt/2mb /dev/rmt/c21t4d0BEST /dev/rmt/c21t4d0BESTnb
/dev/rmt/2mn /dev/rmt/c21t4d0BESTb

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Michael Steele_2
Honored Contributor

Re: Compression to take backup on tape drives

BTW

Unless things have changed recently, firmware and software compression don't work together. So verify with your backup admin that software compression is not being used, else, WTF?
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John Ferro
Regular Advisor

Re: Compression to take backup on tape drives

Thanks we have installed the correct device drivers which will enable compression automatically..

Regards,
OldSchool
Honored Contributor

Re: Compression to take backup on tape drives

Michael:

things *have* changed. most drives (like LT0's) use some from of Loss-less compression. See "LTO-DC" here: http://en.wikipedia.org/wiki/Linear_Tape-Open
Michael Steele_2
Honored Contributor

Re: Compression to take backup on tape drives

Old School:

Wikipedia! You want you site reference from Wikipedia?

I, ...

...don't think I can do that.
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OldSchool
Honored Contributor

Re: Compression to take backup on tape drives

just because its wiki, doesn't mean is wrong...which it isn't in this case