Dne 24.9.2014 v 04:11 lilofile napsal(a):
When I test thinly-provisioned logical volumes,I use dd if=/dev/zero of=/dev/mapper/mythinvolume count=1 bs=4k
I only write 4k data in mythinvolume.but In thin_map functions, I found there are really 4K data written,but I found more read IO,probably dozens of read io. who issue these IO?
Hi
I'd have guessed those I/O are likely metadata update related - at most every
second metadata are synchronized to your metadata storage volume.
(Thin pool consists of _tdata data volume where provisioned chunks are located
and _tmeta metadata volume).
And btw you could use tools like thin_dump to explore how is your pool used,
which chunks belong to which volume, which are share and so on....
Regards
Zdenek
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