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

Thomas Sjolshagen thomas at sjolshagen.net
Tue Feb 15 12:12:25 UTC 2011


On Tue, 15 Feb 2011 12:49:38 +0100, Nikola Savic wrote: 

> This is
interesting approach. I understand that DRBD with GFS2 doesn't require
LVM between, but it does bring some inflexibility:
> * For each
logical volume, one has to setup separate DRBD
> * Cluster wide logical
volume resizing not easy
> * No snapshot - this is very important to me
for MySQL backups.
> 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?

Just so you realize; If you
intend to use clvm (i.e. lvme in a cluster where you expect to be able
to write to the volume from more than one node at/around the same time
w/o a full-on failover), you will _not_ have snapshot support. And no,
this isn't "not supported" as in "nobody to call if you encounter a
problem", it's "not supported" as in "the tools will not let you create
a snapshot of the LV". 

However, you ought to be able to configure one
of the DRBD mirror members as part of a split/mount read-only/merge
based equivalent and thus get a similar result, I think. 

// Thomas 
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