If you use ceph-disk (and I believe ceph-depoly) to create your OSDs, or you go through the manual steps to set up the partition UUIDs, then yes udev and the init script will do all the magic. Your disks can be moved to another box without problems. I've moved disks to different ports on controllers and it all worked just fine. I will be swapping the disks between two boxes today to try to get to the bottom of some problems we have been having, if it doesn't work I'll let you know.
The automagic of ceph OSDS has been refreshing for me because I was worried about having to manage so many disks and mount points, but it is much easier than I anticipated once I used ceph-disk. Robert LeBlanc Sent from a mobile device please excuse any typos. On May 11, 2015 5:32 AM, "Georgios Dimitrakakis" <gior...@acmac.uoc.gr> wrote: > Hi Robert, > > just to make sure I got it correctly: > > Do you mean that the /etc/mtab entries are completely ignored and no > matter what the order > of the /dev/sdX device is Ceph will just mount correctly the osd/ceph-X by > default? > > In addition, assuming that an OSD node fails for a reason other than a > disk problem (e.g. mobo/ram) > if I put its disks on another OSD node (all disks have their journals > with) will Ceph be able to mount > them correctly and continue its operation? > > Regards, > > George > > I have not used ceph-deploy, but it should use ceph-disk for the OSD >> preparation. Ceph-disk creates GPT partitions with specific >> partition UUIDS for data and journals. When udev or init starts the >> OSD, or mounts it to a temp location reads the whoami file and the >> journal, then remounts it in the correct location. There is no need >> for fstab entries or the like. This allows you to easily move OSD >> disks between servers (if you take the journals with it). Its magic! >> But I think I just gave away the secret. >> >> Robert LeBlanc >> >> Sent from a mobile device please excuse any typos. >> On May 7, 2015 5:16 AM, "Georgios Dimitrakakis" wrote: >> >> Indeed it is not necessary to have any OSD entries in the Ceph.conf >>> file >>> but what happens in the event of a disk failure resulting in >>> changing the mount device? >>> >>> For what I can see is that OSDs are mounted from entries in >>> /etc/mtab (I am on CentOS 6.6) >>> like this: >>> >>> /dev/sdj1 /var/lib/ceph/osd/ceph-8 xfs rw,noatime,inode64 0 0 >>> /dev/sdh1 /var/lib/ceph/osd/ceph-6 xfs rw,noatime,inode64 0 0 >>> /dev/sdg1 /var/lib/ceph/osd/ceph-5 xfs rw,noatime,inode64 0 0 >>> /dev/sde1 /var/lib/ceph/osd/ceph-3 xfs rw,noatime,inode64 0 0 >>> /dev/sdi1 /var/lib/ceph/osd/ceph-7 xfs rw,noatime,inode64 0 0 >>> /dev/sdf1 /var/lib/ceph/osd/ceph-4 xfs rw,noatime,inode64 0 0 >>> /dev/sdd1 /var/lib/ceph/osd/ceph-2 xfs rw,noatime,inode64 0 0 >>> /dev/sdk1 /var/lib/ceph/osd/ceph-9 xfs rw,noatime,inode64 0 0 >>> /dev/sdb1 /var/lib/ceph/osd/ceph-0 xfs rw,noatime,inode64 0 0 >>> /dev/sdc1 /var/lib/ceph/osd/ceph-1 xfs rw,noatime,inode64 0 0 >>> >>> So in the event of a disk failure (e.g. disk SDH fails) then in the >>> order the next one will take its place meaning that >>> SDI will be seen as SDH upon next reboot thus it will be mounted as >>> CEPH-6 instead of CEPH-7 and so on...resulting in a problematic >>> configuration (I guess that lots of data will be start moving >>> around, PGs will be misplaced etc.) >>> >>> Correct me if I am wrong but the proper way to mount them would be >>> by using the UUID of the partition. >>> >>> Is it OK if I change the entries in /etc/mtab using the UUID=xxxxxx >>> instead of /dev/sdX1?? >>> >>> Does CEPH try to mount them using a different config file and >>> perhaps exports the entries at boot in /etc/mtab (in the latter case >>> no modification in /etc/mtab will be taken into account)?? >>> >>> I have deployed the Ceph cluster using only the "ceph-deploy" >>> command. Is there a parameter that I ve missed that must be used >>> during deployment in order to specify the mount points using the >>> UUIDs instead of the device names? >>> >>> Regards, >>> >>> George >>> >>> On Wed, 6 May 2015 22:36:14 -0600, Robert LeBlanc wrote: >>> >>> We dont have OSD entries in our Ceph config. They are not needed >>>> if >>>> you dont have specific configs for different OSDs. >>>> >>>> Robert LeBlanc >>>> >>>> Sent from a mobile device please excuse any typos. >>>> On May 6, 2015 7:18 PM, "Florent MONTHEL" wrote: >>>> >>>> Hi teqm, >>>>> >>>>> Is it necessary to indicate in ceph.conf all OSD that we have >>>>> in the >>>>> cluster ? >>>>> we have today reboot a cluster (5 nodes RHEL 6.5) and some OSD >>>>> seem >>>>> to have change ID so crush map not mapped with the reality >>>>> Thanks >>>>> >>>>> FLORENT MONTHEL >>>>> _______________________________________________ >>>>> ceph-users mailing list >>>>> ceph-users@lists.ceph.com [1] [1] >>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com [2] [2] >>>>> >>>> >>>> Links: >>>> ------ >>>> [1] mailto:ceph-users@lists.ceph.com [3] >>>> [2] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com [4] >>>> [3] mailto:florent.mont...@flox-arts.net [5] >>>> >>> >>> _______________________________________________ >>> ceph-users mailing list >>> ceph-users@lists.ceph.com [6] >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com [7] >>> >> >> >> Links: >> ------ >> [1] mailto:ceph-users@lists.ceph.com >> [2] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> [3] mailto:ceph-users@lists.ceph.com >> [4] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> [5] mailto:florent.mont...@flox-arts.net >> [6] mailto:ceph-users@lists.ceph.com >> [7] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> [8] mailto:gior...@acmac.uoc.gr >> > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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