[Linux-cluster] Design question about VG / LV in a clustered environement

[Jeff Sturm]

> -----Original Message-----
> From: linux-cluster-bounces at redhat.com [mailto:linux-cluster-bounces at redhat.com]
> On Behalf Of Nicolas Ross
> Sent: Tuesday, December 06, 2011 1:40 PM
>
> For availibility reasons, we are planing of spliting the /CyberCat (and the other one like
> it) FS into several smaller filesystems, one for each service.

[snip]

> 1. First of all, is this a bad idea ?

Right or wrong, that's how we do it.

Apart from availability, you can tune the fs appropriately depending on how you use it.  GFS2 dropped some tunables, I think, but you can still mount with "noatime" (assuming your application doesn't rely on atime) and tune some things like block size.  Some of our GFS filesystems are also read-only on certain nodes, so we take advantage of spectator mounts for those.

> 2. Is there any disadvantages of doing a single volume group composed of many
> physical volumes, enabling us to move the extents of a logical volume from one
> physical volume to another one, so that load is more balanced in the event we need it.

Can't say, really.  We ditched CLVM but kept GFS.  It felt like CLVM had too many limitations to make it worthwhile.  It was straightforward to just export a LUN from our SAN for each file system, and that allows us to take advantage of the SAN's native snapshot facility.

-Jeff