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I am using an HP Surestore DAT 40x6 tape drive which uses DDS4 tapes to perform
backups using Backup Exec V. 7.3 (rev 2371, NT4 SP6 environment). The tapes
have a capacity of 40 GB however during backups, each tape only backs up
around 22 GB of data. I have set up compression preference (under options)
to "use hardware if available, otherwise use software".
Is there another setting in the software that I need to know about in order
to get the full 40 GB capacity? Please help. Thanks.
Jim
20/40 is a marketing term meaning 20GB uncompressed, 40GB compressed at
at 2:1 ratio (Something rarely acheived in the real world. Depending on
your data type(s) you may get as high a 4-5:1, or as low as 1.1-1.2:1
22GB is about 1.2:1 a little low, but not really anything to get overly
alarmed about
Jim wrote:[color=blue]
>
> I am using an HP Surestore DAT 40x6 tape drive which uses DDS4 tapes to perform
> backups using Backup Exec V. 7.3 (rev 2371, NT4 SP6 environment). The tapes
> have a capacity of 40 GB however during backups, each tape only backs up
> around 22 GB of data. I have set up compression preference (under options)
> to "use hardware if available, otherwise use software".
> Is there another setting in the software that I need to know about in order
> to get the full 40 GB capacity? Please help. Thanks.
>
> Jim[/color]
On 5 Jan 2001 14:16:38 -0500, "Jim" <kababe@sj.counterpane.com> wrote:
[color=blue]
>
>I am using an HP Surestore DAT 40x6 tape drive which uses DDS4 tapes to perform
>backups using Backup Exec V. 7.3 (rev 2371, NT4 SP6 environment). The tapes
>have a capacity of 40 GB however during backups, each tape only backs up
>around 22 GB of data. I have set up compression preference (under options)
>to "use hardware if available, otherwise use software".
>Is there another setting in the software that I need to know about in order
>to get the full 40 GB capacity? Please help. Thanks.
>
>Jim[/color]
On my last backups I got 1.2-1.5-2.1-1.2 : 1 compression. I am using
BENT 7.3 and a DDS2 tape unit in a similar environment. I am using
software compression because of compatibility issues.
I am pretty certain that the capacity of the tapes with compression
will vary as much as this on large datasets, especially if there are a
lot of compact files like jpg images and the like. They do not
compress at all. Quite normal I would say.
Of course you may have an issue with the sales hype, but the fine
print says that compression may vary depending on contents....
Bo Berglund
[email]bo.berglund@telia.com[/email]
Up until a month ago I got ~37 Gb per tape. Now I get ~23 Gb on the same
tapes (both amounts/tape very consistent). I have not yet found out why
(compression is checked on my backups). I'm still investigating, but you
probably don't have to live with 22Gb/tape backups.
Gordon
[email]bo.berglund@telia.com[/email] (Bo Berglund) wrote:[color=blue]
>On 5 Jan 2001 14:16:38 -0500, "Jim" <kababe@sj.counterpane.com> wrote:
>[color=green]
>>
>>I am using an HP Surestore DAT 40x6 tape drive which uses DDS4 tapes to[/color][/color]
perform[color=blue][color=green]
>>backups using Backup Exec V. 7.3 (rev 2371, NT4 SP6 environment). The tapes
>>have a capacity of 40 GB however during backups, each tape only backs[/color][/color]
up[color=blue][color=green]
>>around 22 GB of data. I have set up compression preference (under options)
>>to "use hardware if available, otherwise use software".
>>Is there another setting in the software that I need to know about in order
>>to get the full 40 GB capacity? Please help. Thanks.
>>
>>Jim[/color]
>
>On my last backups I got 1.2-1.5-2.1-1.2 : 1 compression. I am using
>BENT 7.3 and a DDS2 tape unit in a similar environment. I am using
>software compression because of compatibility issues.
>
>I am pretty certain that the capacity of the tapes with compression
>will vary as much as this on large datasets, especially if there are a
>lot of compact files like jpg images and the like. They do not
>compress at all. Quite normal I would say.
>
>Of course you may have an issue with the sales hype, but the fine
>print says that compression may vary depending on contents....
>
>
>
>Bo Berglund
>bo.berglund@telia.com[/color]
I found that I had not been purging a daily compressed db backup onto a large
disk. Noticed the disk was near 80%, purged compressed backups, now the
backups are fine. My bad.
I feel much better now.
"Gordon McKinnon" <dcyspm@yahoo.com> wrote:[color=blue]
>
>Up until a month ago I got ~37 Gb per tape. Now I get ~23 Gb on the same
>tapes (both amounts/tape very consistent). I have not yet found out why
>(compression is checked on my backups). I'm still investigating, but you
>probably don't have to live with 22Gb/tape backups.
>
>Gordon[/color]