An Exchange Information Store is a database. A Standard Exchange Server can host 3 Information Store databases. Each is a Jet database and can exist at its own file path and will have a .edb file extension.
You can manually defrag an Exchange database using a tool called eseutil. In this case, you’ll encounter from 5 to 20 minutes of downtime per gig of the Information Store. You can run eseutil, Eseutil can be run to scan a database to determine whether an offline defragmentation is necessary.
You can run eseutil to manually determine the space that could be saved with a defrag. To do so, run eseutil with the /m and /s options:
eseutil /MS "D:\database\primary.edb"
To run a defrag, specify that you are defragmenting a /d for database and /ds for the directory. You will need enough space on the drive with the edb files on it to make a copy of the database (double-click on an Information Store to see the path). In this example we’ll specify a temporary directory to use for defraging on another volume, as follows:
eseutil /d /ds /tc:D:\backup\eseutildefrag.edb /p
Note: To use a temporary volume, increase the amount of time per gig to defrag the database.
While defrag is something that eseutil can help with, I find that it’s also frequently used for performing recovery operations on a database. To check:
eseutil /r ”D:\database\primary.edb”
To run, use the /P option:
eseutil /P "D:\database\primary.edb"
If you have a corrupt or missing .stm file (according to the version of Exchange, you can create one using the /CREATESTM flag:
eseutil /P /CREATESTM "D:\database\primary.edb"
There are tons of other options available in eseutil. But sometimes the tool cannot run because corruption extends beyond tables and indexes. To chase down corruption, you can also use isinteg. To test a folder on the exchange server called exchange.krypted.com, specify the server using the -s option and indicate -test to run tests as well as the specific test to run, which can be indicated with the alltests option:
isinteg -s exchange.krypted.com -test alltests
You can also specify specific tests, replacing alltests with folder, allacltests, allfoldertests, search, global, etc. These tests all have their own options. To run a repair also add the -fix option.
A lot of corruption can be caused by problems with the service, IO or corrupt volumes. To check volumes, use chkdsk. IO issues often correlate to Event IDs of 10025, 10026 and 10027. Problems with the Information Store service can be varied but should be tracked using the Event Logs and debugging options on a per-service basis.