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