[Gluster-users] Posix locks AFR and high availability

[Krishna Srinivas]

Andrew,
Yes it should work safely. posix-locks can beloaded just above storage/posix.
Let us know if it does not work the correct way.
Krishna

On Mon, Oct 20, 2008 at 3:30 PM, Andrew McGill <list2008 at lunch.za.net> wrote:
> Is it possible to get posix locks in a high availability configuration
> with glusterfs?
>
> Specifically, is it sufficient to have locking enabled on the server side
> below the AFR layer?
>
>
> |glusterfsd....| |.......glusterfs client..
>
>
> [u1]---[u1-lock]---+
>                   :=:--afr0--+
> [u3]---[u3-lock]---+          |
>                              +----client/unify-----
> [u2]---[u2-lock]---+          |  |
>                   :=:--afr0--+  |
> [u4]---[u4-lock]---+             |
>                                 |
> [u5-ns]--------------------------+
>
> Here is part of the server configuration ...
>
> volume u1
>  type storage/posix
>  option directory /glusterfs/u1/export
> end-volume
>
> volume u2
>  type storage/posix
>  option directory /glusterfs/u2/export
> end-volume
>
> volume u1-lock
>  type features/posix-locks
>  subvolumes u1
> end-volume
>
> volume u2-lock
>  type features/posix-locks
>  subvolumes u2
> end-volume
>
> I have a bad feeling that in a race condition, half of the clients will check
> the locks on one brick while the other half will check the other brick ...
> and that simultaneous transactions may be quite happy with getting one out of
> two flocks, or only release one of the two when they are done ...
>
> &:-)
>
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