On Wed, Sep 16, 2009 at 7:26 PM, <william.d.brown AT gsk DOT com> wrote:

What are people using for the fragment size on LTO4 (or I guess LTO3) with
NBU 6.x?

I ask because the default is 1TB, i.e. more or less don't fragment.

The argument for a large fragment is that the backup doesn't have to stop
so often as it does briefly at the end of each fragment to update the
Master, and also the inter-fragment file markers waste space..though
that's hardly a consideration on such large tapes now.

The argument for a small fragment was that the tape can position at full
speed to the file marker for the appropriate fragment for a restore,
rather than reading the tar file from the top at read speed, which for a
large tape could be a very long time.

We used to (dating back to DLT7000) set a 2GB fragment, as back then this
was thought a good idea in case you wanted to dd the tape to disk and read
it without NetBackup.  UNIX file systems did not take files > 2GB.  Well I
can't say we ever tried it and it's a silly small size now.

But what are people using - 100GB?  200GB?  Does it really make a
difference...

William D L Brown


-----------------------------------------------------------
This e-mail was sent by GlaxoSmithKline Services Unlimited
(registered in England and Wales No. 1047315), which is a
member of the GlaxoSmithKline group of companies. The
registered address of GlaxoSmithKline Services Unlimited
is 980 Great West Road, Brentford, Middlesex TW8 9GS.
-----------------------------------------------------------

_______________________________________________
Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu

This email (including any attachments) may contain confidential
and/or privileged information or information otherwise protected
from disclosure. If you are not the intended recipient, please
notify the sender immediately, do not copy this message or any
attachments and do not use it for any purpose or disclose its
content to any person, but delete this message and any attachments
from your system. Astrium disclaims any and all liability if this
email transmission was virus corrupted, altered or falsified.
-o-
Astrium Limited, Registered in England and Wales No. 2449259
Registered Office:
Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2AS, England

_______________________________________________
Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu