KVM Guest I/O slowness

Discussion in 'Technical' started by klocika, Jan 25, 2013.

  1. klocika

    klocika New Member

    Hi all,

    I have a KVM cluster running on CentOS 6.3. All the guests are CentOS 6.3 also. All hosts are connected to a SAN, the base filesystem is gfs2.

    I cloned some mysql cluster nodes from each other, they are on the same LUN, but one of them can do approx. 200 000 IO/sec, the other ones can do only 2-4000 IO/sec.

    My guests use LVM with cache='none' io='native' settings.

    If you have any idea please help me. I think something went wrong with the blocks, but I really don't know, coz the LVMs are on the same LUN and the IO during clone is more then 500000/sec.

  2. falko

    falko Super Moderator ISPConfig Developer

    Have you tried cache='writethrough' and io='threads'?

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