[Whoops, resending as plain text to make vger happy.] On Fri, Jun 1, 2012 at 4:35 AM, Jerker Nyberg <jerker@xxxxxxxxxxxx> wrote: > Cool! No more SSDs (that might fail over being written to continuously > after a couple of months depending in size, prize, write cycles etc) just > add a lot of RAM, keep the journals on tmpfs and make sure to run Ceph on > Btrfs? While keeping the replicas separated so not all fail at once. > > The contents of the storage node will not be corrupt or something (just a > bit old) when losing the journal? The problem with storing things in RAM is, what if your rack/row/data center loses power, all at once. It's really hard to guard against those kinds of massive failures. If you don't have a persistent journal, you might as well not have a journal at all. The memory-only systems you see out there are typically only used to the kinds of applications where rolling back to last (on-disk) snapshot is acceptable -- stuff like shopping carts. Ceph is built on significantly stronger promises, so it's not the ideal match for an architecture like that. It's also unclear to me on what would happen to Ceph if all the replicas lost their journals at the same time. That might cause bigger problems, since there's no up to date replica to pull the lost data from. -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
