On Wed, 31 Oct 2012, Tren Blackburn wrote: > On Wed, Oct 31, 2012 at 2:18 PM, Gandalf Corvotempesta > <gandalf.corvotempe...@gmail.com> wrote: > > In a multi replica cluster (for example, replica = 3) is safe to set > > journal on a tmpfs? > > As fa as I understood with journal enabled all writes are wrote on > > journal and then to disk in a second time. > > If node hangs when datas are still on journal (and journal is not on a > > permanent disk), some data lost could happens. > > > > In a multi replica environment, other nodes should be able to write > > the same datas to disk, right? I this case, using a journal on a tmpfs > > should be safe enough. > > Unless you're using btrfs which writes to the journal and osd fs > concurrently, if you lose the journal device (such as due to a > reboot), you've lost the osd device, requiring it to be remade and > re-added.
This is correct. For non-btrfs file systems we rely on the journal for basic consistency. sage -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
