On Tue, Mar 13, 2012 at 05:46:00PM +0100, Frido Roose wrote:
I'm not sure if this still makes sense on top of GFS2, but that
reminds me
to the fact that you said sanlock was meant to be used with a block device.
Maybe this is something that the libvirtd devs need to be aware of. I'll
start a discussion about this on the libvirt list as the person who tried
to help me didn't understand the delays neither.
The suggested libvirt sanlock setup uses NFS. When using NFS, you
probably want to tune your io timeout so that id_renewal_fail_seconds is
less than the time it takes your NFS server to restart.
id_renewal_fail_seconds is 8*io_timeout, so with a 10 sec io_timeout, your
NFS server would need to restart within 80 seconds, otherwise the vm's
would be killed.
> * io_timeout_seconds: defined by us
> *
> * id_renewal_seconds: defined by us
> *
> * id_renewal_fail_seconds: defined by us
> *
> * watchdog_fire_timeout: /dev/watchdog will fire without being petted
> this long
> * = 60 constant
> *
> * host_dead_seconds: the length of time from the last successful host_id
> * renewal until that host is killed by its watchdog.
> * = id_renewal_fail_seconds + watchdog_fire_timeout
> *
> * delta_large_delay: from the algorithm
> * = id_renewal_seconds + (6 * io_timeout_seconds)
> *
> * delta_short_delay: from the algorithm
> * = 2 * io_timeout_seconds
> *
> * delta_acquire_held_max: max time it can take to successfully
> * acquire a non-free delta lease
> * = io_timeout_seconds (read) +
> * max(delta_large_delay, host_dead_seconds) +
> * io_timeout_seconds (read) +
> * io_timeout_seconds (write) +
> * delta_short_delay +
> * io_timeout_seconds (read)
> *
> * delta_acquire_held_min: min time it can take to successfully
> * acquire a non-free delta lease
> * = max(delta_large_delay, host_dead_seconds)
> *
> * delta_acquire_free_max: max time it can take to successfully
> * acquire a free delta lease.
> * = io_timeout_seconds (read) +
> * io_timeout_seconds (write) +
> * delta_short_delay +
> * io_timeout_seconds (read)
> *
> * delta_acquire_free_min: min time it can take to successfully
> * acquire a free delta lease.
> * = delta_short_delay
> *
> * delta_renew_max: max time it can take to successfully
> * renew a delta lease.
> * = io_timeout_seconds (read) +
> * io_timeout_seconds (write)
> *
> * delta_renew_min: min time it can take to successfully
> * renew a delta lease.
> * = 0
>
>
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