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" <jcputter at gmail.com
> <mailto:jcputter at gmail.com>> 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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>
>
>
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