Hi Jason, Here is my initial attempt at using the Watch/Notify support to be able to remotely fsfreeze a filesystem on a RBD. Please note this was all very new to me and so there will probably be a lot of things that haven't been done in the best way.
https://github.com/fiskn/rbd_freeze I'm not sure if calling out to bash scripts is the best way of doing the fsfreezing, but it was the easiest way I could think to accomplish the task. And it also allowed me to fairly easily run extra checks like seeing if any files have been updated recently. Let me know what you think. Nick > -----Original Message----- > From: ceph-users [mailto:[email protected]] On Behalf Of Nick > Fisk > Sent: 08 July 2016 09:58 > To: [email protected] > Cc: 'ceph-users' <[email protected]> > Subject: Re: [ceph-users] RBD Watch Notify for snapshots > > Thanks Jason, > > I think I'm going to start with a bash script which SSH's into the machine to > check if the process has finished writing and then calls the > fsfreeze as I've got time constraints to getting this working. But I will > definitely revisit this and see if there is something I can create > which will do as you have described, as it would be a much neater solution. > > Nick > > > -----Original Message----- > > From: ceph-users [mailto:[email protected]] On Behalf > > Of Jason Dillaman > > Sent: 08 July 2016 04:02 > > To: [email protected] > > Cc: ceph-users <[email protected]> > > Subject: Re: [ceph-users] RBD Watch Notify for snapshots > > > > librbd pseudo-automatically handles this by flushing the cache to the > > snapshot when a new snapshot is created, but I don't think krbd does the > > same. If it doesn't, it would probably be a nice addition to > the block driver to support the general case. > > > > Baring that (or if you want to involve something like fsfreeze), I > > think the answer depends on how much you are willing to write some > > custom C/C++ code (I don't think the rados python library exposes > > watch/notify APIs). A daemon could register a watch on a custom > > per-host/image/etc object which would sync the disk when a > notification is received. Prior to creating a snapshot, you would need to > send a notification to this object to alert the daemon to > sync/fsfreeze/etc. > > > > On Thu, Jul 7, 2016 at 12:33 PM, Nick Fisk <mailto:[email protected]> wrote: > > Hi All, > > > > I have a RBD mounted to a machine via the kernel client and I wish to > > be able to take a snapshot and mount it to another machine where it can be > > backed up. > > > > The big issue is that I need to make sure that the process writing on > > the source machine is finished and the FS is sync'd before taking the > > snapshot. > > > > My question. Is there something I can do with Watch/Notify to trigger > > this checking/sync process on the source machine before the snapshot is > > actually taken? > > > > Thanks, > > Nick > > > > _______________________________________________ > > ceph-users mailing list > > mailto:[email protected] > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > > > > > > > > > -- > > Jason > > _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list [email protected] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
