[dm-devel] dm-cache issue

[Alexander Pashaliyski]

Hi guys,


I am in a process of evaluating dm-cache for our backup system.

Currently I have an issue when restart the backup server. The server is
booting for hours, because of IO load. It seems is triggered a flush from
SSD disk (that is used for a cache device) to the raid controllers (they
are with slow SATA disks).
I have 10 cached logical volumes in *writethrough mode*, each with 2T of
data over 2 raid controllers. I use a single SSD disk for the cache.
The backup system is with lvm2-2.02.164-1 & kernel 4.4.30.


Do you have any ideas why such flush is triggered? In writethrough cache
mode we shouldn't have dirty blocks in the cache.


Thanks,
Alex
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