Veritas-bu

Re: [Veritas-bu] Mixing block sizes on LTO Media ... Is it bad ?

2007-10-12 06:00:15
Subject: Re: [Veritas-bu] Mixing block sizes on LTO Media ... Is it bad ?
From: Justin Piszcz <jpiszcz AT lucidpixels DOT com>
To: "Wilkinson, Alex" <alex.wilkinson AT dsto.defence.gov DOT au>
Date: Fri, 12 Oct 2007 05:46:51 -0400 (EDT)
Yes it is a very bad idea if you do it when it is running.  If you do it 
when netbackup is stopped and then try and restore you may also run into 
issues.

Justin.

On Fri, 12 Oct 2007, Wilkinson, Alex wrote:

> Hi all,
>
> We are looking at tuning SIZE_DATA_BUFFERS and NUMBER_DATA_BUFFERS to keep our
> LTO{2,3} drives streaming, however, an interesting question has come up within
> our storage group.
>
> Since we interleave blocks from various hosts (grouped by "windows", "unix",
> "Exchange", "Oracle", "Sharepoint", etc etc) and the block size will 
> potentially
> differ when we implement the "SIZE_DATA_BUFFERS" tuning parameter, will this
> cause issues when it comes to doing restores (reading the tapes) ? i.e. some
> blocks on the tape will be 64KB and other blocks will be 256KB.
>
> What are the implications of the aforementioned and is it bad practice ? And 
> is
> there and authoritative method to deal with mixed block sizes written to tape 
> ?
>
> -aW
>
>
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