Enterprise Vault - CAB File Questions

The main complaints about CAB file have to do with unpacking the files in large data migrations and with a perceived performance delay when retreiving cabbed messages. 

One is just planning.  When you have to retreive, move, export, etc...  larger numbers of emails that are in CABs the cab files have to be fully expanded which can take additional space (temporarily).  During large data migrations, especially when changing archive platforms this can be challenging, but not serious when in that situation. 

Second, depending on how old that data is when you cab it there can be some performance impact on access messages due to the requirement that the cab must be fully expanded to retreive a single email.  Generally I don't collect the emails until they are 6 months old.  In this manner I mitigate the activity since the majority of access to archived data is before 6 months.

IMHO, the benefits of collections far outweigh the costs.

i would point out that there's only one single benefit to collections and that's to help with backups and by help i mean mitigate issues due to design flaws or changes in the environment, for example, like the OP mentioned with him having to move the EV data to DataDomain.

the drawbacks begin with what you outlined around performance and data migrations but to add to what you said, the other issues are with any situation that requires reindexing, exports of data for eDiscovery, and storage issues with closed partitions where you dont have enough free space for unpacked CABs or you need to waste space to accomodate for the potential for unpacked CABs.

like with massive migrations, the Move Archive process will also have the same drawbacks with having to unpack every single CAB file related to an archive even if it's just for 1 single email item.

if you loose a CAB file or a CAB becomes corrupt, all the DVS files inside it are impacted which could be in the order of magnitute od 100's of times the impact to just a single corrupt DVS.

and remember, there's no going back once you've enabled collections.