Hi,
There is a secret (as always) configuration file that disable the drive
compression from netbackup. Someone send it to me before some years, but I
cannot find it.
-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Justin
Piszcz
Sent: Wednesday, January 27, 2010 4:07 PM
To: Whelan, Patrick
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Question with Tape Compression: Is it possible to
turnit off?
Hi,
That is in Solaris, correct?
For Linux, per the manpage:
Files
/dev/st* : the auto-rewind SCSI tape devices
/dev/nst* : the non-rewind SCSI tape devices
Do not see a tape drive device that disables compression in Linux.
It does talk about it here:
http://wiki.zmanda.com/index.php/Hardware_compression
From: /etc/stinit.def
manufacturer=XXXXX model = "YYYYY" {
mode1 compression=1
mode2 compression=0
}
The problem though is NBU will turn it on again after the first
initialization.
For Solaris:
Set ST_MODE_SEL_COMP in st.conf for your device and then use the correct
tape device variant (do not use "c" and "u" device)
Even so, I wonder if NBU tries to re-enable it on the drive in Solaris.
Justin.
On Wed, 27 Jan 2010, Whelan, Patrick wrote:
> Could you not specify /dev/rmt/xxubn instead of /dev/rmt/cbn in the
> drive configuration? This would stop compression to the drive always. Of
> course if you are unfortunate enough to be running windows, then you may
> be out of luck.
>
>
> Patrick Whelan
> NetBackup Specialist
> Wholesale Markets and Treasury & Trading
> Lloyds Banking Group
> Desk: +44 (0) 207 158 6123
>
>
> -----Original Message-----
> From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
> [mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Justin
> Piszcz
> Sent: 27 January 2010 13:41
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: [Veritas-bu] Question with Tape Compression: Is it possible to
> turnit off?
>
> Hello,
>
> If you backup highly compressed files, it carries with it anywhere
> between 1-5% overhead overall.
>
> Example: 400GB LTO-3 Tape
> Example: ~367GB and the tape is FULL:
>
> LTO-3 TAPE:
> XXXXXX 9 44 12/10/2009 04:46 12/10/2009 10:13 hcart3
> 367050755 0
> MPX INFINITY N/A FULL
>
> You can disable compression on a tape drive using the mt command,
> however, NetBackup will re-enable it:
>
>> From Symantec:
> There is no direct way to turn off hardware compression from NetBackup.
> If you use mt command to set the compression, it is effective only for
> the currently loaded tape. Once the tape is unloaded the default
> compression setting takes into effect. You will have to contact the
> hardware vendor to disable the tape compression
>
> It is also not possible to disable tape compression on the drives via
> ACSLS (for those who run ACSLS0 with Sun robots.
>
> And the pre and post backup scripts on the client would not help here.
> Basically, there is no 'easy' way to make this work correctly.
>
> The only thing I could think of is if the client called a pre_backup
> script and told the media server, "hey, turn compression off" this might
> work BUT it would only work if MPX=1 or there was no multiplexing as
> there would be other jobs running to that tape drive. In addition, if
> you do have a lot of tape drives on a media server, ugh, you see my
> point.
>
> Any other thoughts on this one?
>
> Justin.
>
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