Half of the paths to the same LUN show lesser throughput as compared to other half.
Issue
- IO throughput is not balanced across all the paths to the LUN.
- Half of the paths to the same LUN show lesser throughput as compared to other half.
- IO Performance degradation in Enterprise array
Out of 4 paths to the LUN, 2 paths are showing one third throughput. IO is balanced unevenly.
01/31/2017 08:43:02 PM
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sdc 0.00 0.00 0.00 3.00 0.00 12.00 8.00 0.00 0.67 0.00 0.67 0.67 0.20
sdd 0.00 0.00 0.00 4.00 0.00 36.00 18.00 0.00 0.00 0.00 0.00 0.00 0.00
sda 0.00 0.00 0.00 20.00 0.00 61440.00 6144.00 0.49 23.75 0.00 23.75 24.75 49.50
sde 0.00 0.00 0.00 21.00 0.00 64512.00 6144.00 0.49 23.52 0.00 23.52 23.38 49.10
sdb 0.00 0.00 0.00 21.00 0.00 21504.00 2048.00 0.15 7.52 0.00 7.52 7.38 15.50
sdf 0.00 0.00 0.00 21.00 0.00 21504.00 2048.00 0.18 8.67 0.00 8.67 8.67 18.20
dm-0 0.00 82.00 0.00 83.00 0.00 168960.00 4071.33 1.32 15.78 0.00 15.78 11.94 99.10
dm-15 0.00 0.00 0.00 6.00 0.00 24.00 8.00 0.00 0.17 0.00 0.17 0.17 0.10
01/31/2017 08:43:03 PM
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sdc 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda 0.00 0.00 0.00 22.00 0.00 67584.00 6144.00 0.48 22.86 0.00 22.86 21.95 48.30
sde 0.00 0.00 0.00 21.00 0.00 64512.00 6144.00 0.50 23.00 0.00 23.00 23.95 50.30
sdb 0.00 0.00 0.00 22.00 0.00 22528.00 2048.00 0.17 7.50 0.00 7.50 7.50 16.50
sdf 0.00 0.00 0.00 21.00 0.00 21504.00 2048.00 0.16 7.81 0.00 7.81 7.81 16.40
dm-0 0.00 86.00 0.00 86.00 0.00 176128.00 4096.00 1.31 15.29 0.00 15.29 11.50 98.90
dm-15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
01/31/2017 08:43:04 PM
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sdc 0.00 0.00 0.00 14.00 0.00 68.00 9.71 0.02 1.43 0.00 1.43 0.43 0.60
sdd 0.00 0.00 0.00 13.00 0.00 64.00 9.85 0.02 1.31 0.00 1.31 0.38 0.50
sda 0.00 0.00 0.00 21.00 0.00 64512.00 6144.00 0.50 23.81 0.00 23.81 23.86 50.10
sde 0.00 0.00 0.00 22.00 0.00 67584.00 6144.00 0.48 22.82 0.00 22.82 21.91 48.20
sdb 0.00 0.00 0.00 21.00 0.00 21504.00 2048.00 0.15 7.33 0.00 7.33 7.33 15.40
sdf 0.00 0.00 0.00 21.00 0.00 21504.00 2048.00 0.16 7.67 0.00 7.67 7.71 16.20
dm-0 0.00 86.00 0.00 85.00 0.00 175104.00 4120.09 1.30 15.49 0.00 15.49 11.56 98.30
dm-15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
01/31/2017 08:43:05 PM
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sdc 0.00 0.00 0.00 1.00 0.00 4.00 8.00 0.00 1.00 0.00 1.00 1.00 0.10
sdd 0.00 0.00 0.00 1.00 0.00 8.00 16.00 0.00 0.00 0.00 0.00 0.00 0.00
sda 0.00 0.00 0.00 21.00 0.00 64512.00 6144.00 0.49 23.48 0.00 23.48 23.48 49.30
sde 0.00 0.00 0.00 21.00 0.00 64512.00 6144.00 0.49 23.19 0.00 23.19 23.19 48.70
sdb 0.00 0.00 0.00 21.00 0.00 21504.00 2048.00 0.15 7.19 0.00 7.19 7.19 15.10
sdf 0.00 0.00 0.00 21.00 0.00 21504.00 2048.00 0.16 7.38 0.00 7.38 7.43 15.60
dm-0 0.00 84.00 0.00 84.00 0.00 172032.00 4096.00 1.29 15.36 0.00 15.36 11.75 98.70
dm-15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
READ as well as WRITE throughput was less for an enterprise array
READ
dd if=/dev/mapper/mpathb of=/dev/null bs=4096k iflag=direct count=1953
1953+0 records in
1953+0 records out
8191475712 bytes (8.2 GB) copied, 36.284 s, 226 MB/s
WRITE
dd if=/dev/zero of=/dev/mapper/mpathb bs=4096k oflag=direct count=1953
1953+0 records in
1953+0 records out
8191475712 bytes (8.2 GB) copied, 53.8566 s, 152 MB/s
Environment
- Red Hat Enterprise Linux 6
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