Robert Milkowski wrote:
Robert Milkowski wrote:
Hi,
When deploying ZFS in cluster environment it would be nice to be able
to have some SSDs as local drives (not on SAN) and when pool switches
over to the other node zfs would pick up the node's local disk drives
as L2ARC.
To better clarify what I mean lets assume there is a 2-node cluster
with 1sx 2540 disk array.
Now lets put 4x SSDs in each node (as internal/local drives). Now
lets assume one zfs pool would be created on top of a lun exported
from 2540. Now 4x local SSDs could be added as L2ARC but because they
are not visible on a 2nd node when cluster does failover it should be
able to pick up the ssd's which are local to the other node.
L2ARC doesn't contain any data which is critical to pool so it
doesn't have to be shared between node. SLOG would be a whole
different story and generally it wouldn't be possible. But L2ARC
should be.
Perhaps a scenario like below should be allowed:
node-1# zpool add mysql cache node-1-ssd1 node-1-ssd2 node1-ssd3
node-1-ssd4
node-1# zpool export mysql
node-2# zpool import mysql
node-2# zpool add mysql cache node-2-ssd1 node-2-ssd2 node2-ssd3
node-2-ssd4
This is assuming that pool can be imported when some of its slog
devices are not accessible.
That way the pool always would have some L2ARC/SSDs not accessible but
would provide L2ARC cache on each node with local SSDs.
Actually it looks like it already works like that!
A pool imports with its cache device unavailable just fine.
Then I added another cache device. And I can still import it with the
first one available but not the 2nd one.
zpool status complains of course but other than that it seems to be
working fine.
Any thought?
--
Robert Milkowski
http://milek.blogspot.com
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