[CentOS] Performance Issues
aspineux at gmail.com
Sun Sep 2 16:24:14 UTC 2007
On 9/2/07, Alain Spineux <aspineux at gmail.com> wrote:
> And what about a
> raw disk tape to raw tape copy ?
raw disk to raw tape copy ?
> # dd if=/dev/sda of=/dev/nst0 bs=32k count=32768
and with time :-)
# time dd if=/dev/sda of=/dev/nst0 bs=32k count=32768
> PS: 14 disk in raid 0 is very fragile, this should be used only for
> caching data. With a PV220 maybe a backup engine then !
> On 9/2/07, Dan Dansereau <ddansereau at hydropoint.com> wrote:
> > My apology for cross posting
> > We have a DELL6850 with 8Gbytes of memory, four 3.2Ghz CPU's , perc 4
> > raid controller, with fourteen 300Gbyte 10Krpm disk on a powervault
> > 220s, And a powervault 124T LTO-3 tape systems on a separate
> > 160Mbyte/sec adaptec SCSI card.
> > The disks are configured as two 2Tbyte raid 0 partitions using the perc
> > 4 hardware.
> > The problem is - reading from the disk, and writing to the tape is
> > pathetically slow.
> > The specs say I should get around 80Mbyte/second - in reality - is about
> > 500 Kbytes/second
> > Writing just to tape, using /dev/zero as input and dd to write, I can
> > get up to 60Mybte/second, indicating that the tape drive and scsi card
> > is functional from a hardware perspective. Since I can read and write
> > data to the disks - I assume that they are functional.
> > The files are 80Mybtes for the minimum size that I am writing to tape.
> > DELL Support hides behind the fact that CENTOS is not a supported OS,
> > But RED HAT is - so switch to it, so DELL can get RED HAT Support
> > involved. And the fact that Rocks is a modification to an unsupported
> > OS....
> > I have tried using various block size in tar from 256 to 8192 - with
> > minimal success.
> > Does anybody have any experience on setting the OS/Kernel parameters to
> > utilize the hardware at something more then a snails pace?
> > Or
> > Suggestions on what I could test and/or try?
> > Or
> > Is there a standard disk / tape IO test package that could test the
> > speed/performance of the disks and /or tapes?
> > Thanks for your help
> > Dan A. Dansereau
> > _______________________________________________
> > CentOS mailing list
> > CentOS at centos.org
> > http://lists.centos.org/mailman/listinfo/centos
> Alain Spineux
> aspineux gmail com
> May the sources be with you
aspineux gmail com
May the sources be with you
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