On 9/2/07, Alain Spineux <aspineux at gmail.com> wrote: > And what about a > raw disk tape to raw tape copy ? ops 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 > -- Alain Spineux aspineux gmail com May the sources be with you