[Gllug] Poor man's SAN - CLVM vs. AoE/OCFS2

Stuart Sears stuart at sjsears.com
Mon Jan 28 20:32:05 UTC 2008

Richard Cottrill wrote:
> Hi people.

Hi Richard :)

> I'm trying to setup a virtual test environment on my PC, and I'd like
> to build some virtualisation into the storage design. There are some
> constraints (as usual):
> - Because the host is Windows and it's not very flexible, I'll use
> Linux as an intermediary/gateway to the storage. Storage will traverse
> the (virtual) network so I'm not limited by the number of virtual IDE
> slots my virtualisation system (VirtualBox/qemu) allows me.
> - Resliance/backup of my "SAN" isn't an issue becuase there's only one
> spindle anyway; so backups will have to be offline (bring the whole
> network down).
> - Using shared/pooled storage is the goal in this case; allowing n-way
> read/write access to data across many (virtual) machines.

> - Speed isn't a huge issue for me (in case you hadn't noticed); but
> clawing any overhead back would be nice.
> - I only tripped over CLVM today while Googling for OCFS2/AoE HOWTOs/references.
> Can anyone share their experiences using CLVM vs. AoE (or
> NBD/iSCSI/etc.) and OCFS2?

not exactly. But...

CLVM does not do the same thing as AoE or iSCSI - it isn't a way of
creating a SAN on the cheap.
It is a way of sharing LVM metadata between nodes in a cluster,
requiring a cluster infrastructure to communicate changes (and only
permitting them if you cluster is quorate and fully functional)

In effect it is a layer on top of AoE or iSCSI, or any other means of
exporting block devices over a network - you still need something to do
this part.


Stuart Sears RHCA etc.

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