-----Original Message----- From: Yong Huang [mailto:yong321@xxxxxxxxx] Sent: Thursday, May 20, 2010 2:28 PM To: Allen, Jack Cc: redhat-list@xxxxxxxxxx Subject: Re: Multipath I/O stats > With multipath set up to access a SAN with some number of LUNs > and for this question 2 paths set for round robin, how can the > I/O stats be seen/gathered to see the throughput on each path > and how balanced the I/O is? I think we can do this. multiptha -l tells you what disks are combined to form a mapper path. Then you can use iostat to check I/O stats of each disk along with each mapper. It won't be hard to write a shell script to re-print the lines of iostat nicely, grouping the lines of the disks under their respective mapper path. Yong Huang =========================== Thanks for the reply. This is the output of just one of the mpaths that I monitored for a while. mpath13 (360060e8005491000000049100000703c) dm-0 HP,OPEN-V [size=10G][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=0][active] \_ 2:0:0:2 sdaa 65:160 [active][undef] \_ 2:0:1:2 sdam 66:96 [active][undef] \_ 1:0:0:2 sdc 8:32 [active][undef] \_ 1:0:1:2 sdo 8:224 [active][undef] Below is the command I used and the results. I know this is a small sampling and I have eliminated the ones that had 0 I/O to save space here. But it appears the I/O is not really being done round-robin as I think it should be. You will notice sdam and sdb are the only ones that do any I/O. Now maybe this is because of some preferred path and controller relationship, I don't know. Any help understanding this would be helpful. iostat -d -p sdaa -p sdam -p sdc -p sdb -p dm-0 2 20 > /tmp/zzxx Linux 2.6.18-164.el5PAE (h0009) 05/20/2010 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 1.53 49.43 15.03 60932848 18523880 sdam 1.53 49.35 15.10 60833016 18616608 sdc 1.53 49.41 15.04 60905568 18542936 sdb 1.38 57.21 3.68 70522704 4533144 dm-0 32.23 197.56 60.24 243542080 74259264 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 4.50 72.00 0.00 144 0 sdc 0.00 0.00 0.00 0 0 sdb 4.50 72.00 0.00 144 0 dm-0 9.00 72.00 0.00 144 0 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 10.00 160.00 0.00 320 0 sdc 0.00 0.00 0.00 0 0 sdb 7.50 112.00 8.00 224 16 dm-0 20.00 160.00 0.00 320 0 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 7.00 112.00 0.00 224 0 sdc 0.00 0.00 0.00 0 0 sdb 5.00 80.00 0.00 160 0 dm-0 14.00 112.00 0.00 224 0 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 3.50 56.00 0.00 112 0 sdc 0.00 0.00 0.00 0 0 sdb 3.50 56.00 0.00 112 0 dm-0 7.00 56.00 0.00 112 0 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 0.50 0.00 7.96 0 16 sdc 0.00 0.00 0.00 0 0 sdb 0.00 0.00 0.00 0 0 dm-0 1.00 0.00 7.96 0 16 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 3.50 32.00 96.00 64 192 sdc 0.00 0.00 0.00 0 0 sdb 0.00 0.00 0.00 0 0 dm-0 16.00 32.00 96.00 64 192 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 0.50 0.00 8.00 0 16 sdc 0.00 0.00 0.00 0 0 sdb 0.00 0.00 0.00 0 0 dm-0 1.00 0.00 8.00 0 16 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 1.50 0.00 24.00 0 48 sdc 0.00 0.00 0.00 0 0 sdb 0.00 0.00 0.00 0 0 dm-0 3.00 0.00 24.00 0 48 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 5.00 24.00 88.00 48 176 sdc 0.00 0.00 0.00 0 0 sdb 0.00 0.00 0.00 0 0 dm-0 14.00 24.00 88.00 48 176 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 0.50 8.00 0.00 16 0 sdc 0.00 0.00 0.00 0 0 sdb 0.00 0.00 0.00 0 0 dm-0 1.00 8.00 0.00 16 0 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdaa 0.00 0.00 0.00 0 0 sdam 7.50 0.00 120.00 0 240 sdc 0.00 0.00 0.00 0 0 sdb 0.00 0.00 0.00 0 0 dm-0 15.00 0.00 120.00 0 240 ----- Jack Allen -- redhat-list mailing list unsubscribe mailto:redhat-list-request@xxxxxxxxxx?subject=unsubscribe https://www.redhat.com/mailman/listinfo/redhat-list
