Thanks Greg and Sage for your replies. Sage's suggestion seems more doable to me. With custom file layout policy, each file would potentially be able to use a customized CRUSH rule. I see that the feature is planned for v0.22. Out of curiosity, what will be an interface for specifying such a policy? Use xattr? Best regards, HS On Wed, Sep 1, 2010 at 4:28 PM, Sage Weil <sage@xxxxxxxxxxxx> wrote: > On Wed, 1 Sep 2010, Gregory Farnum wrote: > >> On Wed, Sep 1, 2010 at 11:33 AM, H Chang <heracles@xxxxxxxxx> wrote: >> > Hi Ceph team, >> > >> > I'm a newbie in Ceph, so please bear with me if my question sounds stupid. >> > >> > I'd like to explore the possibility to support multiple placement >> > policies in Ceph. > > Some of the infrastructure is there for this. Each file has a layout, > which specifies the striping strategy and which storage pool the file data > gets stored. Each pool has a field specifying which CRUSH rule set to use > (they can share). > >> > For example, suppose each user using Ceph has its own placement policy >> > which may be different from one user to another. > > Creating a pool for each user may be overkill, however. The intention was > for pools and/or crush rules to be defined for things like "fast sas > disks", "slow sata pool", that sort of thing. Currently everything is > thrown in a single data pool. > > Currently the default file layout is compiled in and applies to all new > files. There is an open bug/issue for specifying the default file layouts > on a directory basis (e.g, everthing in /home goes into this pool, > everything in /scratch goes in that pool). See > > http://tracker.newdream.net/issues/185 > > In any case, creating per-user pools means pushing more awareness of users > into the file system, autocreating pools, and that sort of thing. As > things stand, the layout policy is something an administrator has to > set up. > >> But it will require changing several pretty low-level structs and >> modifying the metadata server and both versions of the client to >> enable, so it's not a good introductory project and you shouldn't >> expect it soon. :( > > ...for per-user pools, at least. Something along the lines of issue #185 > above is more doable (and on the roadmap). > > sage > >> -Greg >> -- >> 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
