On Wed, 1 Aug 2007 at 11:29am, Jean-Francois Malouin wrote
Hardware: I've setup the default access device to the drives as non-compressing. The library is hooked through a LSI U320 PCI-X scsi card to a 4 DualCore2 Xeon with 8GB of RAM running Debian/Etch running a 64bit kernel 2.6.21.5-i686-64-smp. It should be beefy enough :)
If you ever want to use both drives simultaneously, you'll need a dual channel SCSI card and each drive will need to be on its own channel. Trust me on this one -- I tried every trick I could think of with 2 drives on one channel (there should be plenty of bandwidth, right!?), but couldn't get decent speeds when using both drives.
Running amtapetype with different blocksize gives me ~386MB for capacity (close enough to 400MB) but I never seem to get close to streaming: bs= speed= 32k 50482 kps 128k 50531 kps 256k 50508 kps 512k 50521 kps 1024k 50512 kps 2048k 15780 kps 4096k 15875 kps Any hint on what I should try next?
Interesting. What if you try with dd or tar rather than amtapetype? On my LTO3 drives testing with tar bs=32k yielded 41MiB/s while bs=2048k yielded 60MiB/s.
Note also that LTO drives can throttle back to half of their native rate (80MB/s for LTO3) without shoe-shining.
-- Joshua Baker-LePain Department of Biomedical Engineering Duke University
