# vmstat 1 20
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
0 1 0 181828 109444 2430908 0 0 224 570 18 53 7 2 76 15 0
3 1 0 181432 109444 2430920 0 0 0 2872 6330 28525 13 3 72 11 0
3 2 0 180688 109444 2430928 0 0 20 1416 4625 58510 23 6 53 18 0
0 1 0 180696 109448 2430952 0 0 20 4888 5718 45262 18 7 57 19 0
2 2 0 181068 109460 2430968 0 0 16 4948 3556 38354 15 5 62 18 0
0 4 0 174660 109460 2430972 0 0 4 444 728 1834 1 0 62 37 0
0 2 0 183400 109460 2430492 0 0 28 4632 2050 3338 2 2 66 30 0
0 4 0 171224 109460 2430496 0 0 8 1080 1753 4746 5 1 69 25 0
0 3 0 176564 109464 2430508 0 0 16 8540 2519 6156 4 1 69 25 0
0 3 0 175896 109464 2430532 0 0 12 2308 1423 2340 1 1 60 38 0
0 3 0 176212 109464 2430536 0 0 8 4056 1222 3309 1 0 65 33 0
0 4 0 176568 109476 2430544 0 0 8 5032 2251 6373 2 1 67 30 0
0 3 0 176704 109476 2430548 0 0 4 156 581 1327 0 0 63 36 0
1 2 0 176704 109484 2430568 0 0 24 6028 2195 6464 2 1 73 24 0
0 1 0 177212 109484 2430600 0 0 36 3212 1586 4903 2 1 72 25 0
0 3 0 174104 109492 2430656 0 0 44 2888 2205 3121 6 1 76 16 0
0 2 0 179024 109500 2430948 0 0 44 2496 3841 15326 13 4 68 15 0
3 1 0 179272 109508 2430960 0 0 4 3452 2037 6828 2 1 79 18 0
0 2 0 179156 109512 2430964 0 0 4 884 1208 2787 1 0 84 15 0
0 1 0 179472 109524 2430960 0 0 0 4776 2596 7072 1 1 77 21 0
# iostat -x 1 5
Linux 2.6.32-220.el6.x86_64 (wx-f4-g12-u5-153-43) 2015年04月02日 _x86_64_ (8 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
6.96 0.00 2.21 15.21 0.00 75.61
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.57 667.70 69.41 478.48 3607.82 9169.51 23.32 5.46 9.97 1.44 78.77
avg-cpu: %user %nice %system %iowait %steal %idle
10.03 0.00 2.86 13.93 0.00 73.18
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 9.00 2.00 630.00 16.00 5112.00 8.11 149.59 232.27 1.58 100.00
avg-cpu: %user %nice %system %iowait %steal %idle
3.12 0.00 1.08 12.73 0.00 83.07
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 44.00 1.00 1114.00 8.00 9144.00 8.21 145.52 217.13 0.90 100.00
avg-cpu: %user %nice %system %iowait %steal %idle
5.66 0.00 2.21 11.44 0.00 80.69
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 8.00 1.00 719.00 8.00 5936.00 8.26 143.05 201.54 1.39 100.10
avg-cpu: %user %nice %system %iowait %steal %idle
8.71 0.00 3.48 18.53 0.00 69.28
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 156.00 0.00 213.00 0.00 1704.00 8.00 151.64 186.67 4.69 100.00
很明显，不是cpu瓶颈，是磁盘瓶颈。目前是sas raid1，有必要更换为ssd raid0。
http://en.wikipedia.org/wiki/IOPS
| Device | Type | IOPS | Interface | Notes |
|---|---|---|---|---|
| 7,200 rpm | SATA drives | HDD | ~75-100 IOPS[2] | SATA 3 Gbit/s |
| 10,000 rpm | SATA drives | HDD | ~125-150 IOPS[2] | SATA 3 Gbit/s |
| 10,000 rpm | SAS drives | HDD | ~140 IOPS[2] | SAS |
| 15,000 rpm | SAS drives | HDD | ~175-210 IOPS[2] | SAS |
| SSD drives | >5000 IOPS |