Issue

• iotop で、IO 待ちの割合が高くなっていることが報告されます。

    TIME  TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN      IO    COMMAND
14:09:54 16360 be/3 root        0.00 B/s    0.00 B/s  0.00 % 90.79 % [jbd2/dm-14-8]
14:09:54  1782 be/3 root        0.00 B/s    3.62 K/s  0.00 %  0.28 % [jbd2/dm-9-8]
14:09:54 17099 be/3 root        0.00 B/s    0.00 B/s  0.00 %  0.01 % [jbd2/dm-17-8]
14:09:54 16748 be/3 root        0.00 B/s    0.00 B/s  0.00 %  0.01 % [jbd2/dm-16-8]
...

    TIME  TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN      IO    COMMAND
14:10:19 16360 be/3 root        0.00 B/s 1502.84 K/s  0.00 % 99.99 % [jbd2/dm-14-8]
14:10:19  1782 be/3 root        0.00 B/s    2.89 K/s  0.00 %  6.36 % [jbd2/dm-9-8]
14:10:19 17219 be/4 root        0.00 B/s    0.00 B/s  0.00 %  3.75 % [flush-253:14]
...

• top で、1 つの CPU で iowait 時間が高いことが報告されます。

top - 14:10:06 up 2 days, 12:58,  6 users,  load average:379.38, 85.43, 28.27
Tasks:1908 total,   1 running, 1907 sleeping,   0 stopped,   0 zombie
Cpu0  :1.0%us,  7.5%sy,  0.0%ni, 91.5%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu1  :1.2%us,  8.5%sy,  0.0%ni, 90.3%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu2  :1.4%us,  3.4%sy,  0.0%ni, 95.2%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu3  :4.2%us,  2.0%sy,  0.0%ni, 93.8%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu4  :1.4%us,  5.2%sy,  0.0%ni, 93.4%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu5  :1.0%us,  2.6%sy,  0.0%ni,  0.0%id, 96.4%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu6  :0.6%us,  2.0%sy,  0.0%ni, 97.0%id,  0.4%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu7  :1.2%us,  4.0%sy,  0.0%ni, 94.8%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:32692068k total, 31517304k used,  1174764k free,   348624k buffers
Swap:18874360k total,        0k used, 18874360k free, 21002128k cached