I have a question about right cache policy for KVM using LVM and hardware raid-controller.

So from the bottom: 1. We have LSI RAID controller 9260, 512Mb cache and BBU. Later we also will have CacheCade(SSD Drive as a cache) license and will use SSD. Now controller have virtual drives configured with "write back" and "Disak cache policy:disabled"

  1. Virtual drive presented to LVM. LVM as i know doesn't have any cache policy.

  2. On KVM level - disk attacehd to guest system as virtio-scsi and cache policy set to writethrough.

So question is how to get maximum drive speed in guest and not afraid of power shutdown.

I suppose if i will set virtio-scsi drive policy to "write-back" KVM will use host memory for caching guest io.

So i want to ask if we have optimum configuration now?

Guest system is Windows Server 2012R2 and NTFS. Host system is Centos 6.7 updated.

  • What did your tests tell you? – Michael Hampton Feb 5 '16 at 13:47
  • I cant test power shutdown. Now we dont have Windows 2012R2 guest on host system, but other virtuals are running. But we have applied SSD and CacheCade - so there is a strange behavior now, i suppose raid-controller cache not working now. – user335910 Feb 8 '16 at 9:22

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