Dear all: I agree Robert opinion because I hit the similar problem once. I think that how to handle journal partition is another problem about destroy subcommand. (Although it will work normally most time) I also agree we need the "secure erase" feature. As my experience, I just make new label for disk by "parted" command. I will think how could we do a secure erase or someone have a good idea for this? Anyway, I rework and implement the deactivate first. 2015-01-06 8:42 GMT+08:00 Robert LeBlanc <robert@xxxxxxxxxxxxx>: > I do think the "find a journal partition" code isn't particularly robust. > I've had experiences with ceph-disk trying to create a new partition even > though I had wiped/zapped a disk previously. It would make the operational > component of Ceph much easier with replacing disks if the journal partition > is cleanly removed and able to be reused automatically. > > On Mon, Jan 5, 2015 at 11:18 AM, Sage Weil <sage@xxxxxxxxxxxx> wrote: >> On Mon, 5 Jan 2015, Travis Rhoden wrote: >>> On Mon, Jan 5, 2015 at 12:27 PM, Sage Weil <sage@xxxxxxxxxxxx> wrote: >>> > On Mon, 5 Jan 2015, Travis Rhoden wrote: >>> >> Hi Loic and Wido, >>> >> >>> >> Loic - I agree with you that it makes more sense to implement the core >>> >> of the logic in ceph-disk where it can be re-used by other tools (like >>> >> ceph-deploy) or by administrators directly. There are a lot of >>> >> conventions put in place by ceph-disk such that ceph-disk is the best >>> >> place to undo them as part of clean-up. I'll pursue this with other >>> >> Ceph devs to see if I can get agreement on the best approach. >>> >> >>> >> At a high-level, ceph-disk has two commands that I think could have a >>> >> corollary -- prepare, and activate. >>> >> >>> >> Prepare will format and mkfs a disk/dir as needed to make it usable by Ceph. >>> >> Activate will put the resulting disk/dir into service by allocating an >>> >> OSD ID, creating the cephx key, and marking the init system as needed, >>> >> and finally starting the ceph-osd service. >>> >> >>> >> It seems like there could be two opposite commands that do the following: >>> >> >>> >> deactivate: >>> >> - set "ceph osd out" >>> > >>> > I don't think 'out out' belongs at all. It's redundant (and extra work) >>> > if we remove the osd from the CRUSH map. I would imagine it being a >>> > possibly independent step. I.e., >>> > >>> > - drain (by setting CRUSH weight to 0) >>> > - wait >>> > - deactivate >>> > - (maybe) destroy >>> > >>> > That would make deactivate >>> > >>> >> - stop ceph-osd service if needed >>> >> - remove OSD from CRUSH map >>> >> - remove OSD cephx key >>> >> - deallocate OSD ID >>> >> - remove 'ready', 'active', and INIT-specific files (to Wido's point) >>> >> - umount device and remove mount point >>> > >>> > which I think make sense if the next step is to destroy or to move the >>> > disk to another box. In the latter case the data will likely need to move >>> > to another disk anyway so keeping it around it just a data safety thing >>> > (keep as many copies as possible). >>> > >>> > OTOH, if you clear out the OSD id then deactivate isn't reversible >>> > with activate as the OSD might be a new id even if it isn't moved. An >>> > alternative approach might be >>> > >>> > deactivate: >>> > - stop ceph-osd service if needed >>> > - remove 'ready', 'active', and INIT-specific files (to Wido's point) >>> > - umount device and remove mount point >>> >>> Good point. It would be a very nice result if activate/deactivate >>> were reversible by each other. perhaps that should be the guiding >>> principle, with any additional steps pushed off to other commands, >>> such as destroy... >>> >>> > >>> > destroy: >>> > - remove OSD from CRUSH map >>> > - remove OSD cephx key >>> > - deallocate OSD ID >>> > - destroy data >>> >>> I like this demarcation between deactivate and destroy. >>> >>> > >>> > It's not quite true that the OSD ID should be preserved if the data >>> > is, but I don't think there is harm in associating the two... >>> >>> What if we make destroy data optional by using the --zap flag? Or, >>> since zap is just removing the partition table, do we want to add more >>> of a "secure erase" feature? Almost seems like that is difficult >>> precedent. There are so many ways of trying to "securely" erase data >>> out there that that may be best left to the policies of the cluster >>> administrator(s). In that case, --zap would still be a good middle >>> ground, but you should do more if you want to be extra secure. >> >> Sounds good to me! >> >>> One other question -- should we be doing anything with the journals? >> >> I think destroy should clear the partition type so that it can be reused >> by another OSD. That will need to be tested, though.. I forget how smart >> the "find a journal partiiton" code is (it might blindly try to create a >> new one or something). >> >> sage >> >> >> >>> >>> > >>> > sage >>> > >>> > >>> > >>> >> >>> >> destroy: >>> >> - zap disk (removes partition table and disk content) >>> >> >>> >> A few questions I have from this, though. Is this granular enough? >>> >> If all the steps listed above are done in deactivate, is it useful? >>> >> Or are there usecases we need to cover where some of those steps need >>> >> to be done but not all? Deactivating in this case would be >>> >> permanently removing the disk from the cluster. If you are just >>> >> moving a disk from one host to another, Ceph already supports that >>> >> with no additional steps other than stop service, move disk, start >>> >> service. >>> >> >>> >> Is "destroy" even necessary? It's really just zap at that point, >>> >> which already exists. It only seems necessary to me if we add extra >>> >> functionality, like the ability to do a wipe of some kind first. If >>> >> it is just zap, you could call zap separate or with --zap as an option >>> >> to deactivate. >>> >> >>> >> And all of this would need to be able to fail somewhat gracefully, as >>> >> you would often be dealing with dead/failed disks that may not allow >>> >> these commands to run successfully. That's why I'm wondering if it >>> >> would be best to break the steps currently in "deactivate" into two >>> >> commands -- (1) deactivate: which would deal with commands specific to >>> >> the disk (osd out, stop service, remove marker files, umount) and (2) >>> >> remove: which would undefine the OSD within the cluster (remove from >>> >> CRUSH, remove cephx key, deallocate OSD ID). >>> >> >>> >> I'm mostly talking out loud here. Looking for more ideas, input. :) >>> >> >>> >> - Travis >>> >> >>> >> >>> >> On Sun, Jan 4, 2015 at 6:07 AM, Wido den Hollander <wido@xxxxxxxx> wrote: >>> >> > On 01/02/2015 10:31 PM, Travis Rhoden wrote: >>> >> >> Hi everyone, >>> >> >> >>> >> >> There has been a long-standing request [1] to implement an OSD >>> >> >> "destroy" capability to ceph-deploy. A community user has submitted a >>> >> >> pull request implementing this feature [2]. While the code needs a >>> >> >> bit of work (there are a few things to work out before it would be >>> >> >> ready to merge), I want to verify that the approach is sound before >>> >> >> diving into it. >>> >> >> >>> >> >> As it currently stands, the new feature would do allow for the following: >>> >> >> >>> >> >> ceph-deploy osd destroy <host> --osd-id <id> >>> >> >> >>> >> >> From that command, ceph-deploy would reach out to the host, do "ceph >>> >> >> osd out", stop the ceph-osd service for the OSD, then finish by doing >>> >> >> "ceph osd crush remove", "ceph auth del", and "ceph osd rm". Finally, >>> >> >> it would umount the OSD, typically in /var/lib/ceph/osd/... >>> >> >> >>> >> > >>> >> > Prior to the unmount, shouldn't it also clean up the 'ready' file to >>> >> > prevent the OSD from starting after a reboot? >>> >> > >>> >> > Although it's key has been removed from the cluster it shouldn't matter >>> >> > that much, but it seems a bit cleaner. >>> >> > >>> >> > It could even be more destructive, that if you pass --zap-disk to it, it >>> >> > also runs wipefs or something to clean the whole disk. >>> >> > >>> >> >> >>> >> >> Does this high-level approach seem sane? Anything that is missing >>> >> >> when trying to remove an OSD? >>> >> >> >>> >> >> >>> >> >> There are a few specifics to the current PR that jump out to me as >>> >> >> things to address. The format of the command is a bit rough, as other >>> >> >> "ceph-deploy osd" commands take a list of [host[:disk[:journal]]] args >>> >> >> to specify a bunch of disks/osds to act on at one. But this command >>> >> >> only allows one at a time, by virtue of the --osd-id argument. We >>> >> >> could try to accept [host:disk] and look up the OSD ID from that, or >>> >> >> potentially take [host:ID] as input. >>> >> >> >>> >> >> Additionally, what should be done with the OSD's journal during the >>> >> >> destroy process? Should it be left untouched? >>> >> >> >>> >> >> Should there be any additional barriers to performing such a >>> >> >> destructive command? User confirmation? >>> >> >> >>> >> >> >>> >> >> - Travis >>> >> >> >>> >> >> [1] http://tracker.ceph.com/issues/3480 >>> >> >> [2] https://github.com/ceph/ceph-deploy/pull/254 >>> >> >> -- >>> >> >> 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 >>> >> >> >>> >> > >>> >> > >>> >> > -- >>> >> > Wido den Hollander >>> >> > 42on B.V. >>> >> > Ceph trainer and consultant >>> >> > >>> >> > Phone: +31 (0)20 700 9902 >>> >> > Skype: contact42on >>> >> -- >>> >> 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
