Evan,
On Thu, Dec 07, 2006 at 03:39:05PM -0600, Evan Harris wrote:
>
> I am NOT peaking at 10MB/sec from the amdump report, the 10MB/sec figure is
> from several amtapetest runs, as well as my own manual testing with dd.
>
> I KNOW the tape is shoe-shining, both because I can HEAR it consistently
> having to reposition the tape every few seconds, and because I'm only
> getting 2-3MB/sec average throughput when writing to tape while a dumper is
> running. But I get close to the 10MB/sec when using amflush after all the
> dumpers have completed (under a stripped down testing config where all the
> data fits on and is dumped to the holding disk before the tape is brought
> online).
Oh, that's different. Sorry, I may have missed something in an
earlier email but by the time I started to reply to you this info
was not clear in the thread. Yes, I'd say that was pretty much the
standard diagnostic for shoe-shining.
I've assumed that the spindle the amanda work area is on was dedicated
to the work area and not split, I know nothing about the architecture
of the specific system bus. If you are able to get through put with
amdump than I'd guess its not a bus issue to either the tape nor the
drive. That leaves perhaps CPU or sharing the bus access to the disk
drive ?
But I'm going to have to step back at this point, since it sounds like
a problem specific to a system that I'm not readily able to visualize.
Nor for that matter did I envision CPU or bus activity being sufficiently
intensive that it was blocking the disk to tape IO and I don't know what
tool to suggest monitoring with.
> Evan
>
> On Thu, 7 Dec 2006, Brian Cuttler wrote:
>
> >On Wed, Dec 06, 2006 at 04:33:16PM -0600, Evan Harris wrote:
> >>
> >>Debian testing, SDLT 110/220, Intel P4 2.8Ghz 3gig RAM. Amanda 2.5.1p1-2.
> >>
> >>The holding disk is a dedicated PATA IDE drive (master) on its own
> >>cable/bus (no slave). The tape drive is on its own SCSI bus (no other
> >>devices). Bonnie tests on the IDE drive give roughly 20MB/sec, and I have
> >>no trouble keeping the tape drive streaming using dd from the IDE drive to
> >>the tape drive. Amanda tapetest speed on the tapedrive came in right at
> >>10MB/sec.
> >
> >I have an SDLT 220 also, mine being set for high density but without
> >HW compression, I specifically perform SW compression (client side though
> >in this case the client==server). I am also peaking about 10MB/sec per
> >the amdump report.
> >
> >I have to look at the tape specs... Sun online docs show a sustained
> >transfer rate of 11 MB/Sec, so you and I are both doing pretty well
> >in that dept.
> >
> >Tell me again why you feel your drive is shoe-shining ?
> >Are the specs for your particular drive substantially different ?
> >
> >
> >>I'm currently testing on a standalone SDLT drive first. But the final
> >>config will be the same type of drive in an ADIC changer.
> >>
> >>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
> >>>---
> >>> Brian R Cuttler brian.cuttler AT wadsworth DOT org
> >>> Computer Systems Support (v) 518 486-1697
> >>> Wadsworth Center (f) 518 473-6384
> >>> NYS Department of Health Help Desk 518 473-0773
> >>>
> >---
> > Brian R Cuttler brian.cuttler AT wadsworth DOT org
> > Computer Systems Support (v) 518 486-1697
> > Wadsworth Center (f) 518 473-6384
> > NYS Department of Health Help Desk 518 473-0773
> >
---
Brian R Cuttler brian.cuttler AT wadsworth DOT org
Computer Systems Support (v) 518 486-1697
Wadsworth Center (f) 518 473-6384
NYS Department of Health Help Desk 518 473-0773
|
