Re: [Veritas-bu] Fragment size for LTO4 on NBU 6.x
2009-09-17 04:01:47
This is correct, but does not work at all cases
stefanos
-----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 oersted
Sent: Wednesday, September 16, 2009 5:53 PM
To: VERITAS-BU AT MAILMAN.ENG.AUBURN DOT EDU
Subject: [Veritas-bu] Fragment size for LTO4 on NBU 6.x
tape drive will use LOCATE BLOCK to first file to restore, then search from
there.
wdlb5359 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
>
>
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