6.10 lvm cache issue

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Joined: 2018/07/27 09:27:03

6.10 lvm cache issue

Post by marblerun » 2018/07/27 09:52:42

Some time ago I converted a Dell Cachecade setup to lvmcache, a small 110GB ssd drive in front of a mirrored pair of 2 TB disks.

This has worked quite well, but during the process of moving from 6.9 to 6.10, we noticed that the ssd mirror had degraded, so a failed drive was replaced, firmware updated, etc, etc, and the server was returned to service.

Now, on reboot, the LVM spends about 30 mins syncing, and the server is almost unresponsive as the main disk is fully utilised with I/O

An lvs command will show the Cpy%Sync command slowly dropping to 0.00 - once it reaches this level, I/O activity and responsiveness return to normal.

The other oddity is that the Data% has by this stage reached 100%, which suggests that the cache is full, something I find very hard to believe, as the server was removed from HaProxy, and had no load going through it.

My next course of action is probably to attempt to remove the cache, and perhaps attempt to rebuild. I have seen a previous reference to a similar problem, but it was, I believe, incorrectly diagnosed, and no solution was noted.

kernel version - 2.6.32-754.2.1.el6.x86_64, updates current as of 24th July 2018

Many thanks,


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