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