An interesting thing I just noticed here testing out some Firewire drives with OpenSolaris.
Setup : OpenSolaris 2009.06 and a dev version (snv_129) 2 500Gb Firewire 400 drives with integrated hubs for daisy-chaining (net: 4 devices on the chain) - one SATA bridge - one PATA bridge Created a zpool with both drives as simple vdevs Started a zfs send/recv to backup a local filesystem Watching zpool iostat I see that the total throughput maxes out at about 10MB/s. Thinking that one of the drives may be at fault, I stopped, destroyed the pool and created two separate pools from each drive. Restarting the send/recv to one disk and saw the same max throughput. Tried to the other and got the same thing. Then I started one send/recv to one disk, got the max right away, and started and send/recv to the second one and got about 4MB/second while the first operation dropped to about 6MB/second. It would appear that the bus bandwidth is limited to about 10MB/sec (~80Mbps) which is well below the theoretical 400Mbps that 1394 is supposed to be able to handle. I know that these two disks can go significantly higher since I was seeing 30MB/sec when they were used on Macs previously in the same daisy-chain configuration. I get the same symptoms on both the 2009.06 and the b129 machines. It's not a critical issue to me since these drives will eventually just be used for send/recv backups over a slow link, but it doesn't augur well for the day I need to restore data... Anyone else seen this behaviour with Firewire devices and OpenSolaris? Erik _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
