On Sun, 2 Sep 2007 at 8:11am, Dan Dansereau wrote
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.
Which card and driver? ISTR folks having issues with adaptec cards and LTO3 drives. Might you have a spare LSI SCSI card (ultra320, preferably) about that you could test with?
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
Have you benchmarked the disks to make sure you get decent performance out of them?
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.
80MB total or lots of 80MB files? If the former, you really need to test with, IMO, at least 2X RAM (preferably 4X) sized data to get a reliable speed estimate.
Is there a standard disk / tape IO test package that could test the speed/performance of the disks and /or tapes?
bonnie++ is somewhat standard for testing disk sequential read/write speeds.
-- Joshua Baker-LePain Department of Biomedical Engineering Duke University _______________________________________________ CentOS mailing list CentOS@xxxxxxxxxx http://lists.centos.org/mailman/listinfo/centos
