On Fri, Dec 6, 2013 at 6:16 PM, Josh Durgin <josh.durgin@xxxxxxxxxxx> wrote: > On 12/05/2013 08:58 PM, Gregory Farnum wrote: >> >> On Thu, Dec 5, 2013 at 5:47 PM, Josh Durgin <josh.durgin@xxxxxxxxxxx> >> wrote: >>> >>> On 12/03/2013 03:12 PM, Josh Durgin wrote: >>>> >>>> >>>> These patches allow rbd to block writes instead of returning errors >>>> when OSDs are full enough that the FULL flag is set in the osd map. >>>> This avoids filesystems on top of rbd getting confused by transient >>>> EIOs if the cluster oscillates between full and non-full. >>>> >>>> These are also available in the wip-full branch of ceph-client.git. >>>> >>>> Josh Durgin (3): >>>> libceph: block I/O when PAUSE or FULL osd map flags are set >>>> libceph: add an option to configure client behavior when osds are >>>> full >>>> rbd: document rbd-specific options >>> >>> >>> >>> Due to a race condition between clients and osds in handling maps >>> marked FULL, it's not feasible to offer the 'error' option, so patches >>> 2 and 3 can be ignored. >>> >>> http://tracker.ceph.com/issues/6938 >> >> >> It's not clear to me — are you going to assume all ENOSPC means the >> map is marked as full and intercept it, or that you can't reliably >> block IO so don't bother trying? > > > Don't bother trying to stop ENOSPC on the client side, since it'd need some > restructuring in the kernel side and would be prone to screwing up > write ordering. > > Instead drop writes on the osd side when they have a map marked full, > and have clients resend all writes when a map goes transitions from > full -> nonfull. The userspace side is https://github.com/ceph/ceph/pull/914 Do previous client implementations already satisfy that requirement? We can't drop requests if older clients expect a response... -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com -- 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
