Udev already provides some of this for you. Look in /dev/disk/by-*. You can reference drives by UUID, id or path (for SAS/SCSI/FC/iSCSI/etc) which will provide some consistency across reboots and hardware changes. On Thu, Mar 19, 2015 at 1:10 PM, Colin Corr <colin@xxxxxxxxxxxxx> wrote: > Greetings Cephers, > > I have been lurking on this list for a while, but this is my first inquiry. I have been playing with Ceph for the past 9 months and am in the process of deploying a production Ceph cluster. I am seeking advice on an issue that I have encountered. I do not believe it is a Ceph specific issue, but more of a Linux issue. Technically, its not an issue, just undesired behaviour that I am hoping someone here has encountered and can provide some insight as to a work around. > > Basically, there are occasions when an OSD host machine gets rebooted. Sometimes one or more drives does not spin up properly. This causes the OSD to go offline, along with all other OSDs after it in sequence. > > I created my OSDs using the online docs with the Linux device name (ex. /dev/sdc, sdd, sde, etc). So, osd.0 = /dev/sdc, osd.1 = /dev/sdd, osd.2 = /dev/sde, osd.3 = dev/sdf, etc. > > But, if one of the drives fails/does not spin up, then Linux will rename the drives. Example, /dev/sdd fails on reboot, so now osd.1 comes up with /dev/sde, but /dev/sde is actually the osd.2 drive and osd.2 comes up with what was the osd.3 drive, then they all fall offline in sequence after the one failed osd.1. > > As expected, if I replace the failed drive and reboot, Linux enumerates the drives and gives them the original device names and Ceph behaves properly by marking the affected osd as down and out, while the remaining drives in sequence come up and recover gracefully. > > Does anyone have any thoughts or experience with how one can ensure that Linux device names will always map to the physical device ID? I was thinking along the lines of a udev ruleset for the drives or something similar. Or, is there a better way to create the OSD using the physical device ID? Basically, some sort of way to ensure that a specific physical drive always gets mapped to the same device name and OSD. > > Thanks for any insight or thoughts on this, > > Colin > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
 |