Restores from Online backup fail to Recovery Storage Groups configured on USB storage

You may find that recovery operations from online backup fail when the target of a restore is a Recovery Storage Group that exists on an External USB storage device. Most commonly External USB storage is implemented as a temporary measure due to lack of physical disk space on the server. Thus, the storage is added, an RSG is configured and linked, and a restore is attempted. However, there are a number of "gotchas" you need to be made aware of to allow these operations to complete successfully.

The "general inspiration" for this post was taken from a real case I worked within Customer Support Services.

Primary Issue & Symptoms:

As mentioned above, I recently worked with a customer who was attempting to restore an Exchange 2003 Mailbox Database to a Recovery Storage Group that had been configured on an External USB Hard-Drive. This was done because the available disk space on the production server was not sufficient for restoring the complete mailbox database from backup. Once restored, the customer was going to perform any number of additional recovery operations (single item recovery, complete mailbox, complete database, etc.). What we found was that the restore job would initialize successfully but the byte count never increased above 238 bytes. The restore operation would eventually timeout and fail.

A review of the restore log contained the following information:

Job Completion Status
Job Ended: <time stamp>
Completed Status:  Failed
Final Error:  0xa0008488 -- Access is Denied

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