On Wednesday 21 July 2010 18:26, Sterling James wrote:
>What's compression set to? I know that has other implications, also. Look
>at the makesparsefile option for restore.
>
>"Tivoli Storage Manager backs up a sparse file as a regular file if client
>compression is off. Set the compression option to yes to enable file
>compression when backing up sparse files to minimize network transaction
>time and maximize server storage space. "
I don't know jack about TSM, but based only on that quote and this thread so
far I have to wonder what happens during a restore. If it's using
compression to deal with sparse files, it's probably still compressing all
those empty blocks, right? So on restore, does it decompress them and write
blocks of zeros out instead of re-creating a sparse file? If that's the
case, then it will still try to restore that 26GB sparse file to use 26GB of
DASD, even if it compressed it down to 200MB on the server because of all the
blocks of zeros in it.
Has anyone investigated that problem?
- MacK.
-----
Edmund R. MacKenty
Software Architect
Rocket Software
275 Grove Street · Newton, MA 02466-2272 · USA
Tel: +1.617.614.4321
Email: m...@rs.com
Web: www.rocketsoftware.com
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