Sage, Ideally all the files should go into key/value db (for better portability purpose) but yes, I think we can live with the small partition as you mentioned in the drive for the bootstrap files and creating a sym link under current directory pointing to the other RAW partition on the disk for key/value db to use. But, ceph-disk needs to take care of these things during installation. Is anybody looking into that part ?
Thanks & Regards Somnath -----Original Message----- From: Sage Weil [mailto:[email protected]] Sent: Friday, October 03, 2014 8:03 AM To: Varada Kari Cc: Haomai Wang; Somnath Roy; ceph-devel Subject: RE: Regarding key/value interface On Fri, 3 Oct 2014, Varada Kari wrote: > I am not sure, if Rocksdb/LevelDB can work on a raw device. When I > looked at code they were doing write to mount point/directory. Yeah. But as Somnath points outs others will take a raw device.. I think the main challenge there will be that there is some miscellaneous stuff that Ceph stashes in those directories to bootstrap OSDs. Mainly there's the keyring and a 'done' file. Probably we should add a small file that simply names the backend so that the OSD can start up with an existing store despite a change in ceph.conf. Somnath, I don't think this is particularly problematic, though. The dir can remain and contain a symlink to the raw device. If we want to have hot-swappability, maybe it's possible to carve off a tiny partition on the device? If that doesn't work, we'll have to get more creative (like teach ceph-disk how to interact with the raw device :/). sage > > Varada > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Haomai Wang > Sent: Friday, October 03, 2014 10:55 AM > To: Somnath Roy > Cc: Sage Weil ([email protected]); ceph-devel > Subject: Re: Regarding key/value interface > > Correctly, maybe we can move these super metadata to backend! > > On Fri, Oct 3, 2014 at 6:47 AM, Somnath Roy <[email protected]> wrote: > > Hi Sage/Haomai, > > > > I was going through the key/value store implementation and have one basic > > question regarding the way it is designed. > > > > I think key/value interface is assuming there will be a filesystem on top > > of the device . I saw in mount you are accessing files like > > superblock/fsid. So, for example, /var/lib/ceph/osd/ceph-0 should be a > > filesystem path, right ? > > If so, this may not be the case always as there are key/value stores which > > can work on the raw device. In that case, these files (superblock/fsid) > > also need to go in the key/value db. > > > > Let me know if I am missing anything. > > > > Thanks & Regards > > Somnath > > > > > > > > ________________________________ > > > > PLEASE NOTE: The information contained in this electronic mail message is > > intended only for the use of the designated recipient(s) named above. If > > the reader of this message is not the intended recipient, you are hereby > > notified that you have received this message in error and that any review, > > dissemination, distribution, or copying of this message is strictly > > prohibited. If you have received this communication in error, please notify > > the sender by telephone or e-mail (as shown above) immediately and destroy > > any and all copies of this message in your possession (whether hard copies > > or electronically stored copies). > > > > > > -- > Best Regards, > > Wheat > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" > in the body of a message to [email protected] More majordomo > info at http://vger.kernel.org/majordomo-info.html > N?????r??y??????X???v???)?{.n?????z?]z????ay? ????j ??f???h????? ?w??? ???j:+v???w???????? ????zZ+???????j"????i -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
