Re: Holding Space Size and autoflush

Jon LaBadie wrote:

On Tue, Apr 26, 2005 at 09:49:12AM -0400, Kuas wrote:

I didn't have autoflush turn on before (in amanda.conf), I thought
amanda will flush the content of the holding disk to the tape(=slot,
since I am using file-driver). Is this right? Then I found a problem
with amdump, in the log said that it does not have holding disk anymore.
How big is the holding disk supposed to be? Equal to the size of each
tape? I left it default: use 290 Mb and chunksize 1GB, while my tape
size is 4GB for now.


Think about traditional tapes, not your vtapes.  Only one thing
can be writing to the tape drive at a time.  But ...

I may have 50 clients, each with multiple DLE's.  Do I really
want to dump 1 DLE at a time through hundreds of DLE's?  Probably
not, so I want to be dumping 2, 5, 10, 25 DLE's all at the same
time, but only one thing can be writing to the tape at a time.
The holding disk is used to collect those DLE dumps while they
are in progress and the completed dump until it can be transfered
to tape (the one thing writing to tape remember).

If you use no holding disk, or the available space in the holding
disk is too small, then that DLE is written directly to tape, i.e.
the one thing writing to the tape is a dump in progress, not the
transfer of a completed dump.

Your holding disk is probably doing you no good at all.  Unless
you have several DLE's substantially less than 292MB (maybe incre-
mentals).  And the pair, 292MB with allowed "chunks" of 1GB is
kind of silly.  Tough to fit a 1"G"B chunk on a 292"M"B disk.
Also, if you used defaults, the "reserve" is 100 meaning 100%
of the holding disk can not be used for level 0 dumps, only
incremental.

If your a small installation and don't mind doing one DLE at a
time, eliminate your holding disk.  Otherwise make it larger and
more useful.  I've currently got 3 holding disk pieces, totaling
about 120GB.  For a 9GB nightly run, that gives me lots of space
to hold dumps if I forget to change tapes.  Or it is broken as
it is now.

Thanks for the reply, sorry for the stupid kind of question. I'm reallynew trying to configure it.

Reading back the manual about holding disk, it's kinda strange theholding disk area is smaller than a one-chunk size. I think it should bethe other way around or at least equal. And the value should be as bigat least the size of the tape.

Back to the VTape concept, since the VTape is on the same disk as theholding disk. I don't see any reason why it has to store it temporarilyfirst to the holdingdisk area? Can anybody see the drawback to turnholding-disk off (set to "0") and write all the dumps from the clientstraight to the vtape right away and having the parameter "inparallel=4"so that it will be able to service 4 dump at the same time? The previouscase, after writing to the holding disk, it will have to schedule theflush.


Thanks in advance for any comments.

Kur.