I have a drive that contains an Exchange 2000 database. I have not compressed it yet. If I were to compress the drive to save space, will it backfire or cause problems?
I hope you have not compressed it yet because that will cause problems. Also note that you should never store any file managed by the extensible storage engine (ESE or ESENT) on a compressed drive. Examples of ESE databases included Exchange information stores, Active Directory and the Exchange 2000 instant messaging database.
ESE requires sector independence for log-based recovery, and compression of files invalidates sector independence. Therefore, compression should not be used on volumes hosting ESE databases, or any database that uses write-ahead logging.
See NTFS compressed volume causes store to fail for more information.