[libvirt] libvirt and Parallels Cloud Storage

[Alexander Gordeev]

Hi!

I'd like to develop libvirt integration with Parallels Cloud
Storage (Pstorage) which is a new distributed file system from
Parallels designed specifically for storing VM images:
http://www.parallels.com/products/pcs/cloud-storage/

It's not a POSIX FS but there is a FUSE client for it that can be
used to access and manipulate images. It's quite high speed but only
when used with O_DIRECT + aio. I tried to setup several KVMs on top of
a Pstorage mount using virt-manager. It worked good, but I had to:
1. tune cache and IO settings for every disk
2. disable space allocation by libvirt because it is using sync IO and
is therefore slow

I tried to find ways to solve the first issue and IMHO this can be
done by adding a way to specify per-pool defaults for cache and IO
settings. I didn't find any way for this in the current code and UI.
I'd like to add a new storage backend also that will be a 'dir' backend
with extra ability to manage Pstorage mount points and UI integration.
I'd like to merge my work to the main tree when it's finished if
possible.

What do you think about my plan? Can you please suggest me how to add
per-pool defaults the best way?

-- 
  Alexander