On Wed, Jan 14, 2004 at 03:33:02PM -0500, Brian Cuttler wrote:
> I'm not sure its "planner", what component handles which order DLEs
> are handled in ?

Planner and driver both contribute, I believe:
  - Planner offers a suggested ordering (e.g. it gives priority
    to a DLE that's overdue for a level 0)

  - Driver determines dynamically which dump(s) it can start at
    any given time, based on your "dumporder" amanda.conf
    parameter, the ordering suggested by planner, and on
    available resources -- holding disk space, network bandwidth,
    number of dumps already running on that client, etc.  (N.B.:
    Once a dump has been started, it runs flat-out; Amanda does
    no further throttling.)

> I've got a partition of 54Gig, of which about 36 Gig are in use.
> I've an amanda spool of 35 Gig. Fortunately for us compression
> seems to be working pretty well as we are able to use the work/spool
> area rather than going directly to tape.
> 
> Got me wondering though, is amanda saving this DLE for last so that
> it can utilize all of the spool area by itself or where we just lucky ?

You're *not* just lucky.

I don't think Amanda makes a point of specifically "saving this
DLE for last" (unless your "dumporder" tells it to); that's just
how things work out in your case.  But it does make a point of
saving the DLE until there's holding-disk budget for it -- and,
once the DLE in question has been started, Amanda holds off
starting others if they'd overbook the holding disk.  (It'd be
driver making that sort of decision, btw, not planner.)

> Since this DLE is running 'alone', are we really gaining any performance
> over running in degraded mode ?

I presume you mean "over running in direct-to-tape mode";
degraded mode is something different.

There probably is a gain.  When you dump to disk, taper is
typically (these days, I'd venture to guess almost certainly)
able to provide data (from the holding-disk file) as fast as the
tape drive needs it; but when you dump direct to tape (especially
over the network), that might not be possible.  In the latter
case, the tape transport has to stop and start as data becomes
available -- some people here call that "shoeshining the drive".
That reduces the overall transfer rate, and depending on the tape
technology, possibly (probably?) the amount of data that will fit
on the tape.

Besides, now that you've added a bunch of spool space, the DLE
will no longer necessarily be running alone...

--

|  | /\
|-_|/  >   Eric Siegerman, Toronto, Ont.        erics AT telepres DOT com
|  |  /
It must be said that they would have sounded better if the singer
wouldn't throw his fellow band members to the ground and toss the
drum kit around during songs.
        - Patrick Lenneau