[dm-devel] bcache gets stuck flushing writeback cache when used in combination with LUKS/dm-crypt and non-default bucket size
Tim Small
tim at buttersideup.com
Mon May 16 13:53:46 UTC 2016
On 16/05/16 14:02, Tim Small wrote:
> # iostat -y -d 2 -x -p /dev/sdf /dev/dm-0 /dev/md2 /dev/bcache0
... and then mangled the word-wrapping. Try again:
Here's a typical hand-edited excerpt from:
iostat -d 2 -x -y -m -p /dev/sdf /dev/dm-0 /dev/md2 /dev/bcache0
...
Device: r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await
sdf 396.50 19.50 272.02 0.25 1340.38 138.44 346.09
sdf3 397.00 0.00 272.52 0.00 1405.83 130.05 338.40
dm-0 0.00 149.00 0.00 271.29 3728.81 0.01 0.04
md2 0.00 0.00 0.00 0.00 0.00 0.00 0.00
bcache0 0.00 0.00 0.00 0.00 0.00 0.00 0.00
where:
sdf is the SSD (bcache cache device is sdf3)
dm-0 is dm-crypt backing device (bcache backing store)
md2 is the underlying device for dm-crypt
bcache0 is the bcache device.
According to the iostat manual page:
"avgrq-sz The average size (in sectors) of the requests that were issued
to the device."
dm-0 is described like this in the output of 'dmsetup table':
encryptedstore01: 0 46879675392 crypt aes-xts-plain64
0000000000000000000000000000000000000000000000000000000000000000 0 9:2
3072 1 allow_discards
Tim.
More information about the dm-devel
mailing list