[Gluster-users] parity translator?
joe at julianfamily.org
Mon Feb 18 22:38:03 UTC 2013
On 02/18/2013 01:51 PM, ruben malchow wrote:
> another question that keeps popping up here is this: why isnt there anything like a parity translator that - in combination with striping - takes n+x subvolumes and writes n blocks plus x copies of parity information? wouldn't this make sense for making striping more robust against failures? am i misunderstanding basic concepts again or would a somewhat RAID-like behaviour make it easier to balance robustness against failures against space used?
The short answer is that GlusterFS is not a block device.
Sure, striping exists and could possibly support a parity translator in
RAID fashion, but the stripe translator isn't, imho, anywhere close to
as functional as raid (
http://joejulian.name/blog/should-i-use-stripe-on-glusterfs/ ). Fault
tolerance, self-healing, split-brain, etc. are all much more difficult
to manage when you're not connecting your block storage to the raid
controller and are, instead, storing stripes and parities of files in a
filesystem instead of on blocks.
It's not a definite no, though. 3.4 includes a block-device translator
for exposing raw block devices. Perhaps that could be utilized in a way
that parity striping might eventually happen. I'm sure that if someone
were to write a translator that worked, it would be happily accepted
into the project.
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