On Wed, 25 Feb 2015, Varada Kari wrote: > Hi Sage, > > Thanks. Will wait for your reply. > Meanwhile, Can I submit a blue print for this for next release?
Yeah, definitely. FWIW the plugin layer I think will be most interesting going forward is the ObjectStore level, not just the KeyValueDB level... sage > > Thanks, > Varada > > -----Original Message----- > From: Sage Weil [mailto:[email protected]] > Sent: Tuesday, February 24, 2015 10:21 PM > To: Varada Kari > Cc: Ceph Development > Subject: Re: Adding a proprietary key value store to CEPH > > Hi Varada, > > On Tue, 24 Feb 2015, Varada Kari wrote: > > Hi Sage, > > > > We are trying to integrate a new proprietary key value store to CEPH. To > > integrate this KV-store, which is a closed source shared library, we > > propose a new class to CEPH called PropDBStore which does a dlopen and > > imports the required symbols. This framework will help in integrating > > vendor specific extensions to CEPH. > > > > The gist of the implementation is as follows. > > > > 1. Implement a wrapper around the proprietary KVStore. Let us call it as > > KVExtension. This is a shared library which implements all interfaces > > required by CEPH KeyValueStore. > > 2. A new class is derived from KeyValueDB called PropDBStore, which honors > > the semantics of KeyvalueStore and KeyValueDB. This class acts as mediator > > between CEPH and KVExtension. This class transforms bufferlist etc... to > > const char pointers or strings for the extension to understand. > > 3. PropDBStore, loads (dlopen) the KVExtension during OSD initialization. > > Path to the KVExtension can be mentioned in ceph.conf. > > 4. Interfaces that needs to be implemented in KVExtension, which are > > imported by the PropDBStore are added in a new header called > > PropDBWrapper.h. This header contains the signatures for the necessary > > interfaces like init(), close(), submit_transaction(), get() and > > get_iterator(). Similarly for Iterator functionality, PropDBIterator.h, > > which specifies the signatures of seek_to_first (), seek_to_last(), > > lower_bound() and upper_bound() etc... PropDBStore includes these headers > > to import the symbols, using dlsym(). > > 5. Choosing the proprietary DB as Backend to the OSD is controlled/managed > > by config options of the ceph (/etc/ceph/ceph.conf) like rocksdb or leveldb. > > 6. Rest of the existing functionality is not disturbed by this change. > > Changing the osd backend option will change backend implementation. But > > this change is not dynamic. The type of the backend should be chosen at osd > > creation time and osd will continue use that backend till that osd is > > reformatted again. > > 7. The new KVStore we are trying to integrate works on a raw partition, so > > we divided the osd drive into two partitions. One partition is given to osd > > Meta data (super block, fsid etc...), and the other is given to the new db > > to manage it. OSD partition is now not the entire disk, but 2-4GB which > > needed for the metadata. > > This sounds like a good approach to link to pretty much any external backend > (modulo the dlopen part). I need to check with lawyer types before I can > promise we'll be able to merge something like this into the main ceph.git, > though! > > Thanks- > sage > > ________________________________ > > 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). > > -- > 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 > > -- 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
