Feature request: support for union file systems

[jmartin]

Hi,

is there any chance you can supply a kernel with unionfs and/or aufs enabled in future? They come in really handy when you try to build a number of similar appliances on the same host where each appliance differs only in a few files.

Of course, you can use templates to create these appliances initially, but then you will have to install updates to every one of the appliances instead of being able to upgrade only one instance and see the updates in all of them.

I realize that openvz does not support checkpointing with these filesystems yet, but it support for these filesystems would still be useful.

Regards
Johannes

 

[jmartin]

BTW, OpenVZ can be talked into checkpointing even when aufs, nfs, etc are mounted, see: http://johannes-martin.blogspot.com/2008/05/get-openvz-to-consent-to-checkpointing.html

 

[dietmar]

So why does the OpenVZ people do not enable that by default - there must be a reason?

 

[jmartin]

So why does the OpenVZ people do not enable that by default - there must be a reason?

I assume it's because they don't want to support it officially. When the question arose why xfs wasn't supported for checkpointing, the answer was:

just fix it in the code and you'll be allowed to migrate.
we don't officially suport xfs (since it is incompatible with VZ quotas),
but CPT is not dependent on it and should work.

(see http://openvz.org/pipermail/users/2008-January/001669.html)

It worked fine for me when I tried it last spring, but of course that doesn't mean it will work correctly in all cases...

Anyways, a look at the code suggests that unionfs IS supported, so adding support for that to the kernel (or providing the module in a separator optional .deb) would already help a lot.