On Monday 14 October 2002 04:20, jordivi wrote:
>Hi
>
> My backups fails using soft compression on large disks, using
>tar or dump + gzip I get things like:
>------------------------------------------------------------------
>- FAILURE AND STRANGE DUMP SUMMARY:
> server1 /disk1 lev 0 FAILED [input: Can't read data: :
> Connection timed out] server1 /disk1 lev 0 FAILED [dump to
> tape failed]
>
>Or:
>
>sendbackup: time 890.002: 115: strange(?): sendbackup: index tee
> cannot write [Connection reset by peer]
>sendbackup: time 890.002: index tee cannot write [Connection reset
> by peer]
>sendbackup: time 890.024: pid 22390 finish time Sun Oct 13
> 15:43:39 2002 sendbackup: time 890.026: 91: normal(|): DUMP:
> Broken pipe
>
>Or:
>
>"dumper 0 is messed up, ignoring it"
>ps -fea -> dumper <defunct>
>------------------------------------------------------------------
>-------
>
>So I'm thinking on work without compression (what works fine) and
> turn hw compression on with a bogus tapetype definition. I have:
> # HP Model: C5683A Rev:
> C104 # HP DD-4 40Gb data cartridge C5718A
># HP SureStore DAT40i C5683A. No hw compress. Media DDS4 150m
> HP-C5718A define tapetype DAT40i {
> length 19488 mbytes
> filemark 538 kbytes
> speed 3073 kbytes
>}
>
>Is ok to turn hw compression on and define a tape length about
> 1.8*19488 mbytes? filemark and speed should remain to de above
> values?
Generally speaking, no. Software compression can beat the hardware
almost any day of the year. For instance:
--------------------------
STATISTICS:
Total Full Daily
-------- -------- --------
Estimate Time (hrs:min) 0:49
Run Time (hrs:min) 3:28
Dump Time (hrs:min) 1:24 1:09 0:15
Output Size (meg) 2155.7 1700.1 455.6
Original Size (meg) 6263.6 5447.1 816.5
Avg Compressed Size (%) 32.0 31.2 38.9
Filesystems Dumped 37 2 35
Avg Dump Rate (k/s) 437.8 422.8 504.4
------------------------------
from last nights run here. And I don't compress all 37 entries in
my disklist as some are archives and won't compress further.
Also, as amanda knows the capacity of a tape without compression,
and she counts bytes going to the media after any compression she
might do, its very doubtfull I will ever exceed one tape as long as
runtapes = 1. Amanda will simply defer a level 1 that would
overflow to the next run. You can see that amanda did spend nearly
2 hours doing the compression. If this can be offloaded to
clients, they can be run in parallel, gaining some time even if the
individual client is slower. Here, my only client is the firewall,
and thats rsync'd to a local directory on the server an hour before
the nightly backup.
--
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz 512M
99.18% setiathome rank, not too shabby for a WV hillbilly
