----- Original Message ----- > From: "Berto Bermudez" <[email protected]> > To: "Andrew Martin" <[email protected]>, [email protected] > Sent: Monday, February 17, 2014 2:06:33 PM > Subject: RE: [DRBD-user] Considerations for using bcache on top of DRBD > > You didn't indicate where in your setup the SSDs would sit. I would suggest > you look at also replicating the ssd contents using drbd and layering bcache > on top of that, so that in the event of failover you don't have the penalty > of cold caches. > > HDDs <-- md/raid <-- LVM <-- DRBD <-- bcache |<-- ext4 > SSD<-- DRBD <-- bcache | > > There was a talk about something similar, but using flashcache > http://www.youtube.com/watch?v=l910kiEuHOM > > Berto > Momar, Inc. Hi Berto,
I was intending to keep the SSDs as the top layer, above DRBD. If I understand correctly, you're suggesting creating a separate DRBD device on top of the SSD and then passing that DRBD device to bcache as the cache device, thus propagating the cache changes between nodes? backing device: HDDs <-- md/raid <-- LVM <-- DRBD <-- bcache <-- ext4 cache device: SSDs <-- md/raid <-- DRBD <-- bcache Could this create a problem where during failover the cache device is held open and thus can't be promoted to primary on the other node? In writeback mode this would prevent the device from being usable until the cache device could be failed over successfully. Thanks for the help! Andrew _______________________________________________ drbd-user mailing list [email protected] http://lists.linbit.com/mailman/listinfo/drbd-user
