On Mon, 18 Apr 2016, Peter Rajnoha wrote: > Hi! > > I'm resending original mail to this list after initial > discussion with Loic Dachary so others can chime in. Loic > says these rules were there to workaround certain problems > on Centos 6 only and that it can be discarded now. > > Please, read original mail below: > > === > > We've just noticed 60-ceph-partuuid-workaround.rules. > > You added a patch some time ago which made these rules > to be applied for DM devices too: > > https://github.com/ceph/ceph/commit/42ad86e14e352f2a3a33e774224f1789f268da83 > > The problem we've spotted and hit recently is that > these rules call blkid which opens all DM devices now > on uevents. However, not all DM devices are suitable > for scanning as they may not be prepared fully yet. > We use various flags in DM (and its subsystems like LVM) > to avoid these scans and for all the rules we don't manage, > there's DM_UDEV_DISABLE_OTHER_RULES_FLAG that needs to > be checked in these "foreign" rules before opening such > DM device (which includes running blkid). > > Otherwise, we may end up with errors where some DM subsystem > needs to close the device or do some initialization on this > device before making it public by dropping the > DM_UDEV_DISABLE_OTHER_RULES_FLAG. So we need to make sure > these things are in sync - the scan can't be run on all DM > devices, it's controlled via DM_UDEV_*_FLAG variables. > > Now, when it comes to the 60-ceph-partuuid-workaround.rules, > why do we need that at all? I mean, the 60-persistent-storage.rules > do not whitelist DM devices, so these rules are skipped anyway > and it was that way since beginning, I think. Now, I see this > comment in the 60-ceph-partuuid-workaround.rules: > > # this is a kludge installed by ceph to fix the /dev/disk/by-partuuid > # symlinks on systems with old udev (< 180). it's a stripped down > # version of a newer 60-persistent-storage.rules file that hopefully > # captures the same set of conditions for setting up those symlinks. > > So I need to get to the bottom of the problem which was > resolved here. Feel free to point me to someone else if you're > not the right person, but I need to understand what's behind > these extra workaround rules so I can help to make it work > correctly with DM devices. We added them back when to make the by-partuuid symlinks appear on wheezy: commit d8d7113c35b59902902d487738888567e3a6b933 Author: Sage Weil <sage@xxxxxxxxxxx> Date: Thu May 16 18:40:29 2013 -0700 udev: install disk/by-partuuid rules Wheezy's udev (175-7.2) has broken rules for the /dev/disk/by-partuuid/ symlinks that ceph-disk relies on. Install parallel rules that work. On new udev, this is harmless; old older udev, this will make life better. Fixes: #4865 Backport: cuttlefish Signed-off-by: Sage Weil <sage@xxxxxxxxxxx> On current master, we are not support wheezy (or rhel6) so we should just remove this rule file entirely--it is no longer needed for internfalis, jewel, or later. If you're concerned about hammer, then we need to make sure that it still works on el6, and I'm guessing that is what Loic was working with when we disabled dm-* skipping to make multipath work... 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
