Hi Paul,

thanks for your answer.

> This means that the backup was done in about 12 hours, which would
> have taken more than 4 times as much when doing every DLE sequentially.
> Amanda does dump many clients at the same time.

Ahhhh - ok, it's clear now.
 
> About your problem, the pdf shows that from the 16 dumpers you started,
> only a minority is busy: a peak of 40% in the beginning, and then only
> 1 or even 0 dumpers for a long time.
> At the same time the holdingdisk is used 100%.
> Together it means that your holdingdisk area is too small.
> If possible I would add a cheap large disk in the server (200 Gbyte
> or more would be nice).  You can configure multiple holdingdisks.

i thought 345 GB for my holding disk were ok, since it's half of my total 
storage (that's what the amanda documentation said). I'll try to split the DLEs 
first - if that doesn't help, i'll add some more diskspace.
 
> The graph also shows the tapedrive is (almost) always busy.  That's
> good.  You can fill the little gap with having a larger holdingdisk.
> 
> The total data was 716188 Mbyte and took almost 110:57 - 8:56 = 102:01.
> That is 1996 kB/sec.
> You didn't specify what tapedrive and host server you used, but this
> seems a little low to me.  What is the expected throughput of your
> tapedrive (what does amtapetype indicate as speed)?

i haven't run amtapetype yet, i took the following tapetype definition from 
amanda.org:
define tapetype HPULT2 {
    comment "HP Ultrium 2-SCSI (200G tape used)"
    length 206705 mbytes
    filemark 571 kbytes
    speed 2165 kps
}
maybe i should really run amtapetype, but i'm a bit afraid of the time it 
takes...
 
> My tapedrive is a simple AIT-1 drive, 35 Gbyte native capacity,
> theoretically doing 3MBytes/sec.  Amanda does 2600 kB/sec on
> average (large partitions going at 3000-3090 kB/sec).  And the
> amanda server is only a 300 MHz Celeron with 128 MB RAM and a 80
> Gbyte IDE holdingdisk.

that's interesting. maybe my definition is really false.
 
> Slow tapespeed can be the result of one or more DLE's bypassing
> the holdingdisk.  That results in the tapedrive not streaming anymore.
> The file "amdump.1" contains the keyword "PORT-DUMP" instead of 
> "FILE-DUMP" for such partitions. Are there any?

no, there are only file-dumps.
 
> Again adding holdingdisk space would help in that case (or splitting
> those DLE's into smaller ones).

i'll try that first :-)

> Having a large holdingdisk, and many parallel dumpers, could result
> in doing the dumps fast, finishing before people come in and load
> the client machines, and taping all those collected images can then
> proceed at the normal tapespeed, but without bothering the end users.

i had a look at the tape specs now (which i should have done earlier) - it says 
it can transfer data at 16 MB/s - not only 2 MB/s. I will definitly have to run 
amtapetype now :-}. Let's see, how it's going afterwards.

Thanks a lot,
Kai