[Linux-cluster] Cluster with shared storage on low budget

[Nikola Savic]

Gordan Bobic wrote:
>> What is main reason for you not to use LVM on top of DRBD? Is it just
>> that you didn't require benefits it brings? Or, it makes more
>> problems by your opinion?
>
> Traditionally, CLVM didn't provide any tangible benefits (no
> snapshots), and I never found myself in a situation where dynamically
> growing a volume with randomly assembled storage was required. If you
> are JBOD-ing a bunch of cheap SATA disks, you might as well size the
> storage correctly to begin with and not have to bother with LVM. I'm
> assuming this is what you are doing since you are doing it on the
> cheap (SAN-less). If you are using a SAN, the SAN will provide
> functionality to grow the exported block device and you can just grow
> the fs onto that, without needing LVM.
>
> So apart from snapshots (non-clustered) or a setup like what was
> suggested earlier, to have DRBD on top of local LVM to gain
> local-consistency snapshot capability in a cluster (not sure I'd trust
> that with my data, but it may be good for non-production
> environments), I don't really see the advantage. Snapshots also only
> give you crash-level consistency, which I never felt was good enough
> for applications like databases. A replicated slave that you can shut
> down is generally a more reliable solution for backups.

Thank you for detailed response!

I generally like idea of removing unneeded levels of technology.

In case DRBD+GFS2 is used for shared storage, do I need cluster suite?
Can GFS2 in this setup without cluster setup?

Thanks,
Nikola