This would need to be a new backend, and it's going to be a massive amount of work. You want to start by reading and understanding all of the docs in osd_internals. I also suspect you'll get a lot of what you need from using a replicated cache in front of an EC pool. -Sam
On Fri, Jan 30, 2015 at 10:00 AM, Bassam Tabbara <bassamtabb...@hotmail.com> wrote: > I’d like to explore adding a new EC pool type as you suggest. The idea is to > have RBD sit on-top of a fully functional EC backend. Just as with RAID6 > arrays today some applications are aware of the read-modify-write penalty and > they could optimize for it. > > I’m new to ceph, so if you can point me in the right direction I would > appreciate it. Do you think this is something that could be implemented as a > modification to the existing ECBackend or is this a new backend. I’m happy to > jump on a quick call if it makes things easier. > >> On Jan 30, 2015, at 8:59 AM, Samuel Just <sam.j...@inktank.com> wrote: >> >> Basically, it's an architectural choice: >> >> https://github.com/ceph/ceph/blob/master/doc/dev/osd_internals/erasure_coding/pgbackend.rst#client-writes >> >> If we wanted to support partial writes, we'd probably want to >> introduce a second EC pool type with different tradeoffs. Note, you >> can get slow partial writes on an EC pool by placing a replicated >> cache in front. >> -Sam >> >> On Fri, Jan 30, 2015 at 8:36 AM, Bassam Tabbara >> <bassamtabb...@hotmail.com> wrote: >>> Hello, >>> >>> I realize that the EC Backend does not support all operations like partial >>> writes, truncate, and others. I’d like to understand whether adding the >>> missing operations is something that is architecturally possible, or if >>> this is a limitation of the architecture / approach. Can someone shed some >>> light on this? >>> >>> I realize that partial writes are going to be slow/inefficient on an EC >>> backend compared to a replicated backend. >>> >>> Thanks! >>> Bassam-- >>> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >>> the body of a message to majord...@vger.kernel.org >>> 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 majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
