On Tue, 26 Nov 2013, Christoph Hellwig wrote: > On Tue, Nov 26, 2013 at 11:43:07AM +0100, Dominik Mostowiec wrote: > > Hi, > > I found in doc: http://ceph.com/docs/master/start/os-recommendations/ > > "Putting multiple ceph-osd daemons using XFS or ext4 on the same host > > will not perform as well as they could." > > > > For now recommended filesystem is XFS. > > This means that for the best performance setup should be 1 OSD per host? > > Btw, could anyone clarify where that stance comes from, that is numbers > to back it up. If syncfs(2) is not present, we have to use sync(2). That means you have N daemons calling sync(2) to force a commit on a single fs, but all other mounted fs's are also synced... which means N times the sync(2) calls. Fortunately syncfs(2) has been around for a while now, so this only affects really old distros. And even when glibc does not have a syscall wrapper for it, we try to call the syscall directly. sage -- 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
