You can safely set the clock drift allowed as high as 500ms. The real limitation is that it needs to be well under the lease interval, which is currently 5 seconds by default. You might be able to reproduce more easily by lowering the threshold... sage On Fri, 16 Nov 2012, Nick Bartos wrote: > How far off do the clocks need to be before there is a problem? It > would seem to be hard to ensure a very large cluster has all of it's > nodes synchronized within 50ms (which seems to be the default for "mon > clock drift allowed"). Does the mon clock drift allowed parameter > change anything other than the log messages? Are there any other > tuning options that may help, assuming that this is the issue and it's > not feasible to get the clocks more than 500ms in sync between all > nodes? > > I'm trying to get a good way of reproducing this and get a trace on > the ceph processes to see what they're waiting on. I'll let you know > when I have more info. > > > On Fri, Nov 16, 2012 at 11:16 AM, Sage Weil <sage@xxxxxxxxxxx> wrote: > > I just realized I was mixing up this thread with the other deadlock > > thread. > > > > On Fri, 16 Nov 2012, Nick Bartos wrote: > >> Turns out we're having the 'rbd map' hang on startup again, after we > >> started using the wip-3.5 patch set. How critical is the > >> libceph_protect_ceph_con_open_with_mutex commit? That's the one I > >> removed before which seemed to get rid of the problem (although I'm > >> not completely sure if it completely got rid of it, at least seemed to > >> happen much less often). > >> > >> It seems like we only started having this issue after we started > >> patching the 3.5 ceph client (we started patching to try and get rid > >> of a kernel oops, which the patches seem to have fixed). > > > > Right. That patch fixes a real bug. It also seems pretty unlikely that > > this patch is related to the startup hang. The original log showed clock > > drift on the monitor that could very easily cause this sort of hang. Can > > you confirm that that isn't the case with this recent instance of the > > problem? And/or attach a log? > > > > Thanks- > > sage > > > > > >> > >> > >> On Thu, Nov 15, 2012 at 4:25 PM, Sage Weil <sage@xxxxxxxxxxx> wrote: > >> > On Thu, 15 Nov 2012, Nick Bartos wrote: > >> >> Sorry I guess this e-mail got missed. I believe those patches came > >> >> from the ceph/linux-3.5.5-ceph branch. I'm now using the wip-3.5 > >> >> branch patches, which seem to all be fine. We'll stick with 3.5 and > >> >> this backport for now until we can figure out what's wrong with 3.6. > >> >> > >> >> I typically ignore the wip branches just due to the naming when I'm > >> >> looking for updates. Where should I typically look for updates that > >> >> aren't in released kernels? Also, is there anything else in the wip* > >> >> branches that you think we may find particularly useful? > >> > > >> > You were looking in the right place. The problem was we weren't super > >> > organized with our stable patches, and changed our minds about what to > >> > send upstream. These are 'wip' in the sense that they were in preparation > >> > for going upstream. The goal is to push them to the mainline stable > >> > kernels and ideally not keep them in our tree at all. > >> > > >> > wip-3.5 is an oddity because the mainline stable kernel is EOL'd, but > >> > we're keeping it so that ubuntu can pick it up for quantal. > >> > > >> > I'll make sure these are more clearly marked as stable. > >> > > >> > sage > >> > > >> > > >> >> > >> >> > >> >> On Mon, Nov 12, 2012 at 3:16 PM, Sage Weil <sage@xxxxxxxxxxx> wrote: > >> >> > On Mon, 12 Nov 2012, Nick Bartos wrote: > >> >> >> After removing 8-libceph-protect-ceph_con_open-with-mutex.patch, it > >> >> >> seems we no longer have this hang. > >> >> > > >> >> > Hmm, that's a bit disconcerting. Did this series come from our old 3.5 > >> >> > stable series? I recently prepared a new one that backports *all* of the > >> >> > fixes from 3.6 to 3.5 (and 3.4); see wip-3.5 in ceph-client.git. I would > >> >> > be curious if you see problems with that. > >> >> > > >> >> > So far, with these fixes in place, we have not seen any unexplained kernel > >> >> > crashes in this code. > >> >> > > >> >> > I take it you're going back to a 3.5 kernel because you weren't able to > >> >> > get rid of the sync problem with 3.6? > >> >> > > >> >> > sage > >> >> > > >> >> > > >> >> > > >> >> >> > >> >> >> On Thu, Nov 8, 2012 at 5:43 PM, Josh Durgin <josh.durgin@xxxxxxxxxxx> wrote: > >> >> >> > On 11/08/2012 02:10 PM, Mandell Degerness wrote: > >> >> >> >> > >> >> >> >> We are seeing a somewhat random, but frequent hang on our systems > >> >> >> >> during startup. The hang happens at the point where an "rbd map > >> >> >> >> <rbdvol>" command is run. > >> >> >> >> > >> >> >> >> I've attached the ceph logs from the cluster. The map command happens > >> >> >> >> at Nov 8 18:41:09 on server 172.18.0.15. The process which hung can > >> >> >> >> be seen in the log as 172.18.0.15:0/1143980479. > >> >> >> >> > >> >> >> >> It appears as if the TCP socket is opened to the OSD, but then times > >> >> >> >> out 15 minutes later, the process gets data when the socket is closed > >> >> >> >> on the client server and it retries. > >> >> >> >> > >> >> >> >> Please help. > >> >> >> >> > >> >> >> >> We are using ceph version 0.48.2argonaut > >> >> >> >> (commit:3e02b2fad88c2a95d9c0c86878f10d1beb780bfe). > >> >> >> >> > >> >> >> >> We are using a 3.5.7 kernel with the following list of patches applied: > >> >> >> >> > >> >> >> >> 1-libceph-encapsulate-out-message-data-setup.patch > >> >> >> >> 2-libceph-dont-mark-footer-complete-before-it-is.patch > >> >> >> >> 3-libceph-move-init-of-bio_iter.patch > >> >> >> >> 4-libceph-dont-use-bio_iter-as-a-flag.patch > >> >> >> >> 5-libceph-resubmit-linger-ops-when-pg-mapping-changes.patch > >> >> >> >> 6-libceph-re-initialize-bio_iter-on-start-of-message-receive.patch > >> >> >> >> 7-ceph-close-old-con-before-reopening-on-mds-reconnect.patch > >> >> >> >> 8-libceph-protect-ceph_con_open-with-mutex.patch > >> >> >> >> 9-libceph-reset-connection-retry-on-successfully-negotiation.patch > >> >> >> >> 10-rbd-only-reset-capacity-when-pointing-to-head.patch > >> >> >> >> 11-rbd-set-image-size-when-header-is-updated.patch > >> >> >> >> 12-libceph-fix-crypto-key-null-deref-memory-leak.patch > >> >> >> >> 13-ceph-tolerate-and-warn-on-extraneous-dentry-from-mds.patch > >> >> >> >> 14-ceph-avoid-divide-by-zero-in-__validate_layout.patch > >> >> >> >> 15-rbd-drop-dev-reference-on-error-in-rbd_open.patch > >> >> >> >> 16-ceph-Fix-oops-when-handling-mdsmap-that-decreases-max_mds.patch > >> >> >> >> 17-libceph-check-for-invalid-mapping.patch > >> >> >> >> 18-ceph-propagate-layout-error-on-osd-request-creation.patch > >> >> >> >> 19-rbd-BUG-on-invalid-layout.patch > >> >> >> >> 20-ceph-return-EIO-on-invalid-layout-on-GET_DATALOC-ioctl.patch > >> >> >> >> 21-ceph-avoid-32-bit-page-index-overflow.patch > >> >> >> >> 23-ceph-fix-dentry-reference-leak-in-encode_fh.patch > >> >> >> >> > >> >> >> >> Any suggestions? > >> >> >> > > >> >> >> > > >> >> >> > The log shows your monitors don't have time sychronized enough among > >> >> >> > them to make much progress (including authenticating new connections). > >> >> >> > That's probably the real issue. 0.2s is pretty large clock drift. > >> >> >> > > >> >> >> > > >> >> >> >> One thought is that the following patch (which we could not apply) is > >> >> >> >> what is required: > >> >> >> >> > >> >> >> >> 22-rbd-reset-BACKOFF-if-unable-to-re-queue.patch > >> >> >> > > >> >> >> > > >> >> >> > This is certainly useful too, but I don't think it's the cause of > >> >> >> > the delay in this case. > >> >> >> > > >> >> >> > Josh > >> >> >> > -- > >> >> >> > 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 > >> >> >> -- > >> >> >> 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 > >> >> >> > >> >> >> > >> >> -- > >> >> 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 > >> >> > >> >> > >> -- > >> 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 > >> > >> > > -- 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
