I have dedicated web server with CentOS.
Recently, I get very high server load, probably caused due to IO bottleneck. iostat -mx 3 shows:
avg-cpu: %user %nice %system %iowait %steal %idle
12.15 0.00 19.97 67.89 0.00 0.00
Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util
sda 15.33 6.67 32.67 0.67 2.58 0.03 160.00 0.27 8.20 7.03 23.43
sda1 15.33 6.67 32.67 0.67 2.58 0.03 160.00 0.27 8.20 7.03 23.43
sdb 134.67 0.00 145.33 10.67 13.34 0.19 177.59 131.25 963.31 6.41 100.03
sdb1 134.67 0.00 145.33 10.67 13.34 0.19 177.59 131.25 963.31 6.41 100.03
sdc 0.00 17.33 0.33 21.00 0.00 0.15 14.50 0.08 3.84 0.31 0.67
sdc1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdc2 0.00 14.33 0.33 9.33 0.00 0.09 19.86 0.04 4.28 0.48 0.47
sdc3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdc4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdc5 0.00 0.67 0.00 4.33 0.00 0.02 9.23 0.02 4.85 0.46 0.20
sdc6 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdc7 0.00 2.33 0.00 7.33 0.00 0.04 10.55 0.02 2.68 0.18 0.13
sdc8 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
what can be done to improve performance? My web server reads lots of big files from that HD drive. does 13MB/s for HDD sata2 is a reasonable value? I would expect it to be higher.
top output (head only):
Cpu(s): 7.5%us, 5.5%sy, 0.0%ni, 4.1%id, 71.5%wa, 3.0%hi, 8.5%si, 0.0%st
Mem: 2048144k total, 2036732k used, 11412k free, 23732k buffers
Swap: 8385888k total, 192k used, 8385696k free, 1375064k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
15369 apache 15 0 116m 9.8m 3564 S 3.3 0.5 0:01.37 httpd
23491 apache 15 0 117m 10m 3644 S 3.3 0.5 0:00.55 httpd
21694 mysql 25 0 308m 49m 4752 S 3.0 2.5 1068:49 mysqld
25735 apache 15 0 117m 10m 3660 S 2.7 0.5 0:00.53 httpd
25909 apache 15 0 116m 9964 3548 S 1.0 0.5 0:00.15 httpd
14814 apache 15 0 117m 10m 3684 S 0.7 0.5 0:00.53 httpd
15708 apache 15 0 117m 9.9m 3564 S 0.7 0.5 0:00.66 httpd
21464 apache 15 0 117m 10m 3664 S 0.7 0.5 0:01.32 httpd
22997 apache 15 0 116m 9.8m 3656 R 0.7 0.5 0:04.16 httpd
23484 apache 15 0 117m 10m 3668 S 0.7 0.5 0:00.28 httpd
thanks