MySQL on a virtual machine is gradually slowing down, what could be the reason?

The effect is manifested after a few months, approximately six months. On a dedicated server doing virtualization KVM and up dev on QCOW2 disk image file to a preset size. Start the database server on it and nothing more. Everything works fine for a few months, and then begins to gradually slow down - increasing the number of slow queries to the Slow Log.

It would seem linearly with increasing load, but no. If you do reinstall new path everything is back to normal. I don't remember exactly, but seems to be additionally influenced reinstal OS on a physical server. Is it me or is it not a coincidence? Because reinstal new path/servers once in a quarter/six months is not an option. To know the reason for this phenomenon. I can tell why this is happening?

About 20GB of database queries a lot. Table large on 25M lines. Slow queries become regardless of their complexity and appear in batches. Apparently the problem is in the drive/image, but what exactly, I don't know. As I understand it, increasing the response speed of the disk, and with it the queries slow down.
June 26th 19 at 14:33
2 answers
June 26th 19 at 14:35
For a long time and a long time studying the issue, it's not virtual reality at all. The trouble all modern hypervisors, carrying more than one path, in a joint access drive. What is your average load on the hypervisor? Surely, the dev with MySQL than one?
on the hypervisor of the increase from Oct 1 to 8 now. On virtualke from 0.5 to 5
Yes, now 6 virtuallock on this server. CPU and memory are more than enough. - yvonne75 commented on June 26th 19 at 14:38
probably the drives you have sata/sas/scsi. My hard-won experience suggests that the transportation of your farm on the ssd will solve all the existing problems. - Shakira.Cruickshank commented on June 26th 19 at 14:41
> the drives you have sata/sas/scsi

This is an interface.

SSD type. SSD are both sata and sas, and PCI-E
The stupidity of what you wrote. - presley.Mertz70 commented on June 26th 19 at 14:44
: good luck in the fights) - Shakira.Cruickshank commented on June 26th 19 at 14:47
June 26th 19 at 14:37
for starters do not use qcow and optimizethe of faluji on the host and the guest

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