Fileshare databases are supported for all of the IMSDBU functions, although you should avoid using Fileshare databases with IMSDBU when possible. Considerable performance gains can be achieved by accessing a database as an exclusive-use database. Exclusive-use databases can be on a local hard drive or accessed from a network redirected drive. Even when accessed through network redirection, exclusive-use databases will be much faster than Fileshare databases. However, using exclusive-use databases might not be a practical option in some environments. For example:
IMSDBU requires the MFIMS Supervisor to be installed for Fileshare databases. Performing a LOAD, UNLOAD, REORGANIZE, PTRUPDATE, or USEQ function to a Fileshare database without the Supervisor installed results in an error message.
IMSDBU functions require an exclusive database lock. No users can access a database while an IMSDBU function is running against it. If IMSDBU is unable to acquire an exclusive database lock, the function terminates and an error message is issued. The User ID of the lock holder is displayed in the message. The User ID is configured in the IMSGEN TM/MFS System Configuration.
For the Load and PtrUpdate functions, an automatic commit is issued periodically. The frequency of the commit is configured using the DB System Configuration. The configuration setting is the Maximum Updates Before Warning Pop-up. IMSDBU will issue a commit whenever the number of segments updated exceeds this value. No pop-up warning is issued.
IMSDBU may become locked out of a database during Load or PtrUpdate processing. This can occur when the exclusive database lock is temporarily released while IMSDBU performs its periodic commit. If a user is in 'lock retry' when IMSDBU begins commit processing, the user may be able to acquire the lock while it is temporarily released. If this happens, IMSDBU will timeout and report the failure.