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Re: DLT 8000 and tape type.
2005-01-20 07:23:58
Neil Marjoram wrote:
The DLT 8000 drive can take 80GB compressed,
That's just an advertising claim which is based on assumption that your
data can be compressed 2:1. Such compression ratio is rarely seen
outside the fantasy world of advertising, though.
the results return 40GB.
That means that your tape drive's hardware compression is turned off.
That's fine. This is the recommended setting for Amanda. That does *not*
mean that you can only put 40 GB worth of your data on that tape.
Amstatus shows that the amount of data stored on each tape is always
less than 40G, the latest output from the status is :
tape 1 : 66 27906885k 25125884k ( 68.13%) AG3600
tape 2 : 1 9085868k 9327611k ( 22.18%) AG3602
tape 3 : 0 0k 0k ( 0.00%) AG3598
My question is two part, a. how do I get amanda to backup 80GB to the
DLT,
Add the "compress client fast" or "compress server fast" parameter to
your dumptype. You are not guaranteed to get 80 GB on tape that way. You
may get less or you may get more (although that is quite unlikely). That
depends how well your data can be compressed.
and secondly why is it that the second tape in a three part backup
never holds as much data as the first tape?
I guess that depends of the order in which your disk list entries are
put to tape. Probably, after putting those 9 GB on the second tape,
Amanda started taping a DLE that is bigger than the remaining free space
on that tape. So she hit EOT and started over with this DLE on next
tape. Amanda cannot span one single DLE across multiple tapes.
--
Toomas Aas --------------------------------------------------------
|arvutivõrgu peaspetsialist | head specialist on computer networks|
|Tartu Linnakantselei | Tartu City Office |
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