The reason for the long (42 second) ping-timeout is because re-establishing fd's and locks can be a very expensive operation. Allowing a longer time to reestablish connections is logical, unless you have servers that frequently die.

If you shut down a server through the normal kill process, the TCP connections will be closed properly. The client will be aware that the server is going away and there will be no timeout. This allows server maintenance without encountering that issue.

One issue with a 42 second timeout is that ext4 may detect an error and remount itself read only should that happen while the VM is running. You can override this behavior by specifying the mount option, "errors=continue" in fstab ("errors=remount-ro" is the default). The default can be changed, as well, by changing the superblock option with tune2fs.

On 10/22/2013 03:12 AM, John Mark Walker wrote:

Hi JC,

Yes, the default is a 42-second timeout for failover. You can configure that to be a smaller window.

-JM

On Oct 22, 2013 10:57 AM, "JC Putter" <[email protected] <mailto:[email protected]>> wrote:

    Hi,

    I am new to GlusterFS, i am trying to accomplish something which i am
    not 100% sure is the correct use case but hear me out.

    I want to use GlusterFS to host KVM VM's, from what I've read this was
    not recommended due to poor write performance however since
    libgfapi/qemu 1.3  this is now viable ?


    Currently i'am testing out GlusterFS with two nodes, both running as
    server and client

    i have the following Volume:

    Volume Name: DATA
    Type: Replicate
    Volume ID: eaa7746b-a1c1-4959-ad7d-743ac519f86a
    Status: Started
    Number of Bricks: 1 x 2 = 2
    Transport-type: tcp
    Bricks:
    Brick1: glusterfs1.example.com:/data
    Brick2: glusterfs2.example.com:/data


    and mounting the brick locally on each server as /mnt/gluster,
    replication works and everything but as soon as i kill one node, the
    directory /mnt/gluster/ becomes unavailable for 30/40 seconds

    log shows

    [2013-10-22 11:55:48.055571] W [socket.c:514:__socket_rwv]
    0-DATA-client-0: readv failed (No data available)


    Thanks in advance!
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