looking for a feedback integrating celerra/centera and commvault archive

I think the thread title says it all.

We are currently casting around for an archive solution. We already use the following;

Celerra

Commvault

We are looking at implementing an archiving solution and want to get some feedback from anyone ideally using centera + commvault.

This is based on the working assumption that commvault archive module is needed to talk to the celerra API to determine what files are candidates for archiving and therefore can be moved to the centera.

Also I am interesting in getting some pro's/con's of leaving a stub or simply moving the origional file.

Should the commvault archive engine be unavailable, is the impact simply stopping continued archiving, or is it involved in any way with data retrieval after the candidate file has been archived.

Can the pro's/con's of using a centera as opposed to storage presented as a lun and then as a filesystem be outlined.

Should the max expansion size of a centera be reached, what is required architecturally to implement a second centera to archive from the same celerra ?