[Veritas-bu] Fragment size settings
MarelP at AUSTRALIA.Stortek.com
Thu Oct 18 19:13:47 CDT 2001
Jason, thats exactly what I think
and thats how ASM (STK product) does its backups.
Unless we clarify it alot of people here
may change a setting they otherwise would not
and should not. Thats why I raised my point to
From: Jason Ahrens [mailto:jason.ahrens at telus.com]
Sent: Friday, 19 October 2001 2:28 AM
To: Veritas-bu at mailman.eng.auburn.edu
Subject: RE: [Veritas-bu] Fragment size settings
On Fri, 19 Oct 2001, Marelas, Peter wrote:
> Hmm. If thats the case Im very surprised since
> Ive never heard anyone complain about Netbackup taking
> a very long time to restore a file.
> The fragment size by default is 0 which I believe
> means unlimited. Based on my logic, unlimited is bound
> to EOT.
> If it turns out to be true I think the default is
> a very bad choice.
> My -guess- is fragment size is more geared towards disk
> storage units.
> If I get time to test it I will post a conclusion.
I may be way off base here, but I think NetBackup also stores the file
offset within the tar file. Most drives will allow seeking to a particular
offset on the tape and, if the program supports it somehow, you can read
directly out of the middle of the archive. I would not be surprised if
this is what NetBackup does.
We have our fragment size set to 0 and have never had to wait more than
about a minute for NetBackup to find what it is looking for for a restore,
regardless of where on the tape the data is stored.
However if I ever needed to do a restore using tar from the command line,
smaller fragments would definitly be a huge bonus.
Systems Administrator/Backup Specialist
PSINet Canada Inc., a TELUS company
The Future is Friendly
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