Is Offline defrag worth it ???
Ive seen in the past that its a normal practice of Exchange admins to perform offline defrag aka eseutil /d on exchange databases.
But, is it really worth the time taken and downtime planned ??
To know this better, we need to discuss about event id: 1221 and its relevance.
|Event Source:||MSExchangeIS Mailbox Store|
|Description:||The database “First Storage Group\Mailbox Store (SERVER)” has 3.4 megabytes of free space after online defragmentation has terminated.|
What does this mean ?
Exchange has performed a routine maintenance and any old data that is past the delete thresholds has been deleted from the database.
The space it has left behind has then been converted into “white space”. No difference in the size of the database.
This “white space” will be used by Exchange, before expanding the database any larger.
When to think about reclaiming the white space?
This is my personal opinion:
If the DB is 100 gigs and 1221 says that it has more than 40-50 Gigs free space, it’s worth performing an offline defrag.
What if we don’t reclaim the space ?
This is the real catch –> Exchange will use that space before further increasing the PHYSICAL size of the DB.
Day 1,Event id: 1221 showed my DB has 10 MB of White space. Day 2 it showed the DB has 15 MB of white space. Day 3 its showed 2 MB of white space. What does this mean ?
This means that user might have deleted data worth 10 MB and when maintenance completed Exchange made 10 MB white spaces whilst performing the routine tasks. Day 2, the scenario is not that different because users might have deleted mails or the deleted items retention period is past and exchange could allocate 15 MB white space. Day3, mails might have came in drastically and the WHITE SPACES where used by incoming mails or there wasn’t much job for maintenance to perform, so the process could only give 2 MB.
Other than event id: 1221, is there a way I could find the logical size of DB?
Another option to know the logical size of the Db is to run a eseutil /ms whilst store is offline — Multiple the value by 4 and divide it by 1024 to get the value in MB.
Post a defrag on an exchange database, we might end up in a situation where we need to re-configure all/many Blackberry- iPhone- Windows mobile’s with the new database.
So long story short – Do you really wanna defrag your exchange database ??
Do it iff your’e running out of disc space or the Database has reached its size limit 75GB (E2K3 STD). If not, i’d just let it run….