Hi, I've setup a nullio iscsi target on a server. (and also a dm-zero deviced exported as an iscsi target) This server has 3 network cards. Each card has an ip in it's own subnet. I'm using a linux client. It also has 3 network cards and they are setup in the same subnets. The client opens 3 sessions to the iscsi target. Each session using its own network card. (verified) Both quad core intel cpu servers are running Debian/Etch amd64. (linux 2.6.22, iscsitarget 0.4.15, multipath 0.4.7) I'm using a simple multibus multipath setup. multipath -ll gives: test (1000000000000000000000000000000000000000000000000) dm-8 IET,VIRTUAL-DISK [size=466T][features=0][hwhandler=0] \_ round-robin 0 [prio=6][active] \_ 9:0:0:0 sdd 8:48 [active][ready] \_ 10:0:0:0 sde 8:64 [active][ready] \_ 11:0:0:0 sdf 8:80 [active][ready] I've been doing simple checks with dd and I'm surprised by the results. dd if=/dev/zero of=/dev/dm-8 bs=4k count=10M 10485760+0 records in 10485760+0 records out 42949672960 bytes (43 GB) copied, 137.751 seconds, 312 MB/s dd of=/dev/null if=/dev/dm-8 bs=4k count=10M 10485760+0 records in 10485760+0 records out 42949672960 bytes (43 GB) copied, 364.401 seconds, 118 MB/s How is it 3 times slower when reading from the multipath device ? Watching the network load, i can see the traffic is span to the 3 network cards. and FYI: dd of=/dev/null if=/dev/sdd bs=4k count=2M & dd of=/dev/null if=/dev/sde bs=4k count=2M & dd of=/dev/null if=/dev/sdf bs=4k count=2M & gives: 8589934592 bytes (8.6 GB) copied, 87.7679 seconds, 97.9 MB/s 8589934592 bytes (8.6 GB) copied, 87.877 seconds, 97.7 MB/s 8589934592 bytes (8.6 GB) copied, 101.354 seconds, 84.8 MB/s I first discovered this behavior with a real fileio target and I thought it would be better to narrow things down. I'm pretty sure I must be doing something wrong. In the hope this is not off-topic, could you give me some hints ? Cheers -- -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
