[Gluster-devel] [RFC] Generating custom volume files for gluster volumes

[John Mark Walker]

Hi Bharata,

It might make sense to start pushing this discussion and associated docs to the wiki, using the feature template. You could fill out the feature template, and then create a page in your user space as the feature "home" where you could point people to for any ongoing discussion. Sound good? 

For reference:

Feature template: http://www.gluster.org/community/documentation/index.php/Features/Feature_Template
Current new features list: http://www.gluster.org/community/documentation/index.php/Features
See also 3.4 planning: http://www.gluster.org/community/documentation/index.php/Planning34


-JM


----- Bharata B Rao <bharata.rao at gmail.com> wrote:
> Hi,
> 
> I  have discussed this briefly with some gluster developers over IRC,
> but thought of bringing this up here since I would like to propose
> this as a feature for 3.4 once we have consensus on this.
> 
> With QEMU supporting GlusterFS backend natively, it is good to
> 
> - have a direct IO path from QEMU to its VM image on gluster backend
> - optionally not use those client and server side translators that are
> detrimental to VM's performance.
> 
> If QEMU is running on the machine that hosts the brick, we could avoid
> the overhead of client, server xlators and RPC communication
> overhead by doing IO to the VM image directly using just the posix
> xlator or any other leaf xlator as the case may be. Hence QEMU user
> needs a general  capability to generate volume file with user
> specified xlator set and specific capability to generate volume file
> for RPC bypass scenario.
> 
> Its already possible to specify a custom extension to the volume name
> and glusterd picks the appropriate volume file. For eg, for a volname
> of test.cust, glusterd is capable of picking test.cust.vol. We plan to
> piggy back on this feature and name the custom volume files with
> .custom extension.
> 
> Typical gluster CLI commands needed could be like this:
> 
> gluster> volume regenerate testvol custom --without-io-cache --with-quick-read
> 
> This would create testvol.custom without io-cache and with quick-read xlators.
> 
> This is just an example and not really cast in stone. Need community's
> opinion on this. Should we use existing options like "volume set" or
> invent new ones ?
> 
> Should we allow such flexibility when creating volumes or should we
> provide such capability only when regenerating volume files  for a
> given volume ?
> 
> I would like to know gluster community's thoughts and concerns on this
> before starting work on this.
> 
> Regards,
> Bharata.
> -- 
> http://bharata.sulekha.com/blog/posts.htm, http://raobharata.wordpress.com/
> 
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