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?
>
>(I use amanda version 2.4.3)

Generally speaking, no.  Software compression has two advantages
1. It beats the socks off hardware ratios.  From last nights  run 
here:
--------------------------------
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   
(level:#disks ...)
Filesystems Dumped           37          2         35   (1:34 2:1)
Avg Dump Rate (k/s)       437.8      422.8      504.4
---------------------------------
as you can see, it did spend by inference, about 2 hours doing that 
compression.  At 1:45 am, thats ok by me.

2. it doesn't hide the tapes true size from amanda.

The output size is well below one tape here, and runtapes is set to 
1.  I have seen amanda delay a level 1 to the next night to prevent 
hitting EOT, so I don't think it will ever do that here.

Using hardware compression with amanda is not a Good Thing(tm).

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
99.18% setiathome rank, not too shabby for a WV hillbilly