Ok so this may not be a straight choice for most and an archive solution can complement Exchange for many environments, but there are some who have not yet deployed an archive solution and who can look at it as a straight choice – small mailboxes and an archive solution or big mailboxes and no archive…
Well first things first; you probably need to look at this within the wider context of data management and if longer term data archival for other services that your company operates is in place it may make more sense to deploy an archive solution for Exchange. ..and certainly if your business is mandated to retain data for a certain number of years then a combination of Exchange journaling and message archival may be the only solution to satisfy this requirement. It’s unlikely unfortunately that you would be able to satisfy a retention policy solely within the constraints of your Exchange organisation…
But if it does look like a straight choice then these are some of the areas I’d focus on:
Cost – deploy Exchange 2007 with big mailboxes on DAS and this may be a cheaper solution than a combination of Exchange and its storage, archive software licenses and the storage required for archiving.. Exchange 2007 means that it is now possible to deploy more and bigger mailboxes per server, still get the performance you need and crucially not spend a fortune on expensive storage. It used to be more cut and dry – you had to deploy Exchange on expensive storage to get the performance and the resilience which made it sensible to deploy an archive solution which extended the size of your mailboxes but which sat happily archiving away on ‘cheap’ storage…. The situation has changed with Exchange 2007 and will again with E14.
Accessibility – can all clients (via OWA for example) get access to their archive at all times? The whole mailbox is available to all modes of access if the data is within the mailbox – if it’s archived this may limit access to some of their data.. Check with the archive vendors.
Management – an archive solution requires a different type of management and skills. It means deploying a different type of storage most likely and so you’ll need skills in-house to manage that storage… You’re also going to need skills in managing the archive software and the databases they’re built on (e.g. SQL Server). Do you have the skills in-house to manage the software properly…?
Availability – can the archive solution provide the same levels of availability and resilience as provided by Exchange for your mailbox data? If you need a highly available\resilient messaging environment that covers all messaging data it might be expensive and complicated to meet your SLA’s within the confines of an archive solution. And should the worse happen and you lose a data centre for example, who manages the recovery of both the Exchange environment and the archive?
Anyway just some thoughts. I don’t actually see many deployments these days without an archive solution in one form or another but if there is anyone left it’s worth having the discussion at least before you make your move…
Have a look at some of our partner products in this field @ Exchange Server 2007 Partners: Back-up and Archive
..and I have to mention item counts at this point. ..as everyone knows if you archive mailboxes but leave stubs you don’t reduce the item count in your Outlook folders which will gradually lead to performance problems… Check with your vendor because some solutions have ways around this now.