[linux-lvm] ubuntu xenial + lvmlockd

[linux-lvm] ubuntu xenial + lvmlockd

[Charles Koprowski]

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Hi all,

I'm trying to set up a shared VG between 2 ubuntu servers (xenial) using
lvmlockd for locking.

Unfortunately, even if the default config (lvm.conf) mentions the
possibillity to use lvmlockd (use_lvmlockd = 1), I cannot find any trace of
the daemon lvmlockd or lvmlockctl tool in ubuntu.

Does anyone already done this before ?

Do I have to build lvm from source in order to use lvmlockd ?

Thanks

Regards,

Charles

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Re: [linux-lvm] ubuntu xenial + lvmlockd

[David Teigland]

On Thu, Apr 13, 2017 at 06:14:54PM +0200, Charles Koprowski wrote:
> Hi all,
> 
> I'm trying to set up a shared VG between 2 ubuntu servers (xenial) using
> lvmlockd for locking.
> 
> Unfortunately, even if the default config (lvm.conf) mentions the
> possibillity to use lvmlockd (use_lvmlockd = 1), I cannot find any trace of
> the daemon lvmlockd or lvmlockctl tool in ubuntu.
> 
> Does anyone already done this before ?
> 
> Do I have to build lvm from source in order to use lvmlockd ?

I'd guess that lvm was not built with lvmlockd support, in which case you
would need to rebuild it with one or both of --enable-lockd-sanlock,
--enable-lockd-dlm (and I'm going to rename those options to be "lvmlockd"
in a minute.)

Dave

Re: [linux-lvm] ubuntu xenial + lvmlockd

[Charles Koprowski]

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2017-04-18 18:00 GMT+02:00 David Teigland <teigland@redhat.com>:

> On Thu, Apr 13, 2017 at 06:14:54PM +0200, Charles Koprowski wrote:
> > Hi all,
> >
> > I'm trying to set up a shared VG between 2 ubuntu servers (xenial) using
> > lvmlockd for locking.
> >
> > Unfortunately, even if the default config (lvm.conf) mentions the
> > possibillity to use lvmlockd (use_lvmlockd = 1), I cannot find any trace
> of
> > the daemon lvmlockd or lvmlockctl tool in ubuntu.
> >
> > Does anyone already done this before ?
> >
> > Do I have to build lvm from source in order to use lvmlockd ?
>
> I'd guess that lvm was not built with lvmlockd support, in which case you
> would need to rebuild it with one or both of --enable-lockd-sanlock,
> --enable-lockd-dlm (and I'm going to rename those options to be "lvmlockd"
> in a minute.)
>

Thank you David !

Would you consider the use of lvmlockd + sanlock as "production ready" ?

My goal here is to replace an existing cluster of 5 nodes using clvmd + dlm
+ corosync to access a shared VG of 6 TB containing around 300 LVs.

The current solution is working fine but I find using dlm + corosync "just"
for locking a bit overkill.

Regards,

Charles

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Re: [linux-lvm] ubuntu xenial + lvmlockd

[David Teigland]

On Thu, Apr 20, 2017 at 11:26:18AM +0200, Charles Koprowski wrote:
> Would you consider the use of lvmlockd + sanlock as "production ready" ?

I believe it will work better than clvmd.  There is one main thing, unique
to using sanlock, that you should verify in your environment.
lvmlockd+sanlock is sensitive to spikes in i/o delays.  If sanlock sees
several consecutive large i/o delays (> 10 sec each), e.g. during heavy
use from applications, or during path switching, this can trigger spurious
failure detection.  (This is analogous to network delays when using
network-based solutions.)

(We can increase i/o timeouts to compensate if really necessary.)

> My goal here is to replace an existing cluster of 5 nodes using clvmd + dlm
> + corosync to access a shared VG of 6 TB containing around 300 LVs.
> 
> The current solution is working fine but I find using dlm + corosync "just"
> for locking a bit overkill.

I agree.

Dave