It can be whatever you want it to be from a client perspective. Vault Cache has no storage impact on the server as VC is essentially a feature so that users are able to access their archived content when they are offline from the network.

In the desktop policy you can create the maximum size of the VC or a maximum perccentage of free space that it will take up. From the help it states:-

these settings to specify how to limit the size of a Vault Cache. If a Vault Cache reaches the specified size, the oldest items are automatically deleted to make room for new items. The space is not allocated until it is needed.

Maximum use of initial free space. Select this setting and specify a percentage to limit the maximum size for a Vault Cache as a percentage of the unused disk space that is available when the Vault Cache is created.

Maximum size. Select this setting and specify a value to limit the maximum size for a Vault Cache as a size in gigabytes. The maximum allowed value is 999 GB.

From a server perspective, I guess it would depend on the amount of space you have allocated to the Cache area on your server (right click server in VAC, go to Cache tab and set).   It won't grow any larger than the amount you have set for Cache (default is 20GB).

When the PST files are being built (in preparation for download to the client) they take up space, but are then removed once downloaded to the client.  You can limit the max number of concurrent updates from the default of 10 if required to reduce load.  You could calculate the space required by taking the avg size of a users VC x concurrent connections to get an idea.

Something I noticed today about the Cache area is that if you're installing EV in a cluster you are not able to create the cache on a local disk, it has to be on shared disk (which makes sense really seeing as you can failover to the other node and continue to build the VC).

BZ