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Asked: 2016-04-05 04:41:37 +0800 CST

No w/s in iostat output even though wMB/s is high

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I am trying to format a 2 TB SAN based block device (/dev/mapper/mpathb). Even though, mke2fs has been running since over one hour without completing, iostat -z -x -m 10 output in a separate terminal shows a surprising thing: There are no completed write requests (w/s) even though number of sectors written to disk (wMB/s) is pretty high.

Device:         rrqm/s   wrqm/s     r/s     w/s    rMB/s    wMB/s avgrq-sz avgqu-sz   await  svctm  %util

dm-0      0.00     0.00    0.00    0.10     0.00   204.80 4194304.00     1.00 11036.00 10000.00 100.00
dm-2      0.00     0.00    0.00    0.10     0.00   204.80 4194304.00     1.00 11036.00 10000.00 100.00

Hardly anything changes in iostat output: write speed remains high while number of sectors written remains zero! Any ideas?

storage-area-network

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