Hello,
Does anyone have a good link which outlines symptoms for different performance issues related to IO? I am looking for data I can compare to my IOSTAT or VMSTAT output. For example, I am trying to see if my disk is thrashing..does anyone have output on vmstat or iostat from when there disk was thrashing..
would be more helpfull if you post your output and try to explain where your problems are...
Vada,
disks are only thrashing when you are very low in memory and your systems is permanently paging in and out.
Disks being busy up to 70% is normal on AIX and no reason for concern ... are you trying to investigate high IO waits from cpu? What kind of applications do you run?
I agree with DukeNuke, it would be more helpful if we could see your stats to tell you more than fishing in the dark.
Rgds
zxmaus
Stats are posted below.
IOSTAT:
avg-cpu: %user %nice %sys %iowait %idle
0.75 0.00 3.33 22.56 73.36
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util
sda 38.00 59.33 500.00 12.33 19373.33 573.33 9686.67 286.67 38.93 1.52 2.96 1.76 90.00
sdb 0.00 76.67 1.00 39.33 5.33 760.00 2.67 380.00 18.98 2.73 634.89 3.41 13.77
avg-cpu: %user %nice %sys %iowait %idle
1.08 0.00 4.41 28.73 65.78
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util
sda 20.33 0.00 506.00 0.67 25728.00 5.33 12864.00 2.67 50.79 1.29 2.55 1.88 95.40
sdb 0.00 4528.33 0.00 89.33 0.00 36949.33 0.00 18474.67 413.61 43.44 486.30 4.16 37.20
MPSTAT:
04:00:20 AM CPU %user %nice %system %iowait %irq %soft %idle intr/s
04:00:21 AM all 2.50 0.00 5.75 21.00 0.00 0.00 70.75 2102.02
04:00:22 AM all 0.00 0.00 1.75 23.31 0.00 0.25 74.69 1784.00
04:00:23 AM all 0.50 0.00 2.49 22.94 0.25 0.00 73.82 1779.00
Average: all 1.00 0.00 3.33 22.42 0.08 0.08 73.08 1887.63
VMSTAT:
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
12 2 1416976 45892 423720 12917860 0 0 16 28 1 1 1 1 98 0
0 1 1416976 24188 424548 12941932 0 92 14264 656 2082 4831 3 6 71 21
0 1 1417020 20924 424868 12945332 0 484 8136 1344 1785 4556 0 2 75 23
SAR -B:
03:30:01 AM pgpgin/s pgpgout/s fault/s majflt/s
03:40:01 AM 0.38 41.41 3438.90 0.01
03:50:01 AM 0.09 47.06 3719.47 0.00
04:00:01 AM 1811.48 2079.85 3900.20 0.01
Average: 603.94 722.73 3686.15 0.01
04:02:40 AM LINUX RESTART