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 [EMAIL PROTECTED] > >>> 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 [EMAIL PROTECTED] > > 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 [EMAIL PROTECTED] Computer Systems Support (v) 518 486-1697 Wadsworth Center (f) 518 473-6384 NYS Department of Health Help Desk 518 473-0773
