We currently have an group of about 200 users that are utilizing .pst's as an archiving/organization solution. These pst's are currently stored on a fileserver local to these users, however this fileserver is being moved to our new Enterprise datacenter, and moving these pst's off-site will negatively impact the performance of this configuration. The group is asking the messaging team what options they have for importing the pst's into their mailboxes. For most of the users this *should* be acheivable, however we will NEED to be able to accurately plan for the additional capacity requirements. My question is this: is there a way to accurately "predict" the increase in mailbox size that we will see after we import these pst's? In my experience, pst file size isnt necessarily an good predictor of how much data is actually contained within. However, perhaps there is a tool or a method we can use to analyze or compress these pst's so that we could get a more accurate picture of the storage we'll need to allocate for these mailboxes (scanpst or contig perhaps?). appreciate any input or recommendations - thanks! jm

Nope. It can vary widely. I have seen everything from twice the size of the PST to less than half. PST files can have white space in them for example. It can also depend on attachments and corrupt items. If you have been storing PST files on a network share (which is not supported) then you are likely to have corruption. I usually work on double, and review that as the process goes through. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources