Debian testing, SDLT 110/220, Intel P4 2.8Ghz 3gig RAM.  Amanda 2.5.1p1-2.

Evan

On Wed, 6 Dec 2006, Brian Cuttler wrote:

Evan,

What OS, type of tape, type of drive, HW platform ?

I'm unfamiliar with a parameter to do what your asking
for for good measure, what version of Amanda ?

Actually, how did you determine that a drive within a changer
was shoe-shining ? What else shares the bus with the tape and
with the amanda work area drive(s) ?

On Wed, Dec 06, 2006 at 02:34:31PM -0600, Evan Harris wrote:

I'm having a problem with my tape drive shoe-shining because the holding
disk can't keep up with the tape drive if it is also being written to by a
dumper.  Without the extra disk seek overhead of dumpers writing to the
holding disk at the same time, the holding disk should be plenty fast
enough to keep the tape drive streaming.

Is there any way I can force amanda to serialize the dumper/taper so that
they are never run concurrently?  I've already set inparallel to 1, but
that only affects how many dumpers can run, not the taper.

I've also tried increasing the tapebufs parameter to 8000 (256MiB) to see
if that would at least let the drive stay streaming for longer periods, but
if it made any difference, it wasn't significant.  What thresholds does the
taper use to decide when the tapebufs are filled enough to start tape
motion?  There doesn't seem to be any docs on that, or settings to
customize.

I did get a suggestion that I should just leave the tape out of the drive,
let the dumpers fill the holding disk and then load the tape and run
amflush, but that doesn't really work when using a changer, plus the
holding disk isn't large enough for the total size of all the backups,
though it can fit them one-by-one.

Seems like there should be a "speed" config option for holding disks like
there is for network interfaces and tape drives, so that amanda could test
to see if the holding disk can't handle dumpers using the holding disk at
the same time a taper is running.  That seems like it'd solve the problem
nicely, and even seems to fit with the scheme amanda uses for network
interfaces.

Thanks.

Evan

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  Brian R Cuttler                 brian.cuttler AT wadsworth DOT org
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