Skip to main content

Do we need to file-level defragment Exchange database drives?

 Do we need to file-level defragment Exchange database drives?

Every so often there is a question: "Should we run file-level defragmentation software on Exchange servers?"
Usually, this comes from confusion that file system defragmentation actually helps Exchange as - well, Exchange databases get fragmented too.
The process of Exchange database fragmentation is a completely different story though - it is the defragmentation of the "white space" or empty database pages within the Exchange database. There are 2 types of defragmentation of Exchange databases:
ONLINE defragmentation - this is what happens as part of online maintenance which is by default run on nightly basis. Here we rearrange the data (database pages really) within the database to have more contiguous white space. Typically you will want to make sure that your backup schedule does NOT interfere with online maintenance schedule, as starting of online backup will stop the online defrag.
OFFLINE defragmentation - this is what happens when you run ESEUTIL utility with the /d switch - therefore you need to take the database offline to do it. This is typically done only when there is a specific reason to do it - such as reclaiming huge amounts of hard drive space, if instructed to do so by Support Services when troubleshooting a specific problem, or after a database hard repair (which is another thing that we should never do).
So - that being said - what about file system defragmentation?
I would never do it on running production server databases. The reason for it is simple actually - file system defrag is a very intense I/O operation. So the disc will be very busy. I have seen some cases here in Support Services, where our database engine has actually started logging warnings that the write to the disc was successful, but it took "unusually long" to complete, and it was suggesting that hardware might be at fault. Sure enough - a disk defrag kicked off just before this started happening as witnessed by the Application log. That right there is enough reason for me not to do it in real life.
The bottom line really is - you do not HAVE to file-level defrag the Exchange database drives. Exchange reads and writes to it's databases in very random fashion. Large sequential reads and writes will see much more improvement from file system defrag than Exchange databases will. But if you really WANT to do it - I would do it the old-fashioned way: move the databases off to some other volume, file system defrag the drive and then move the databases back... Or at least make sure you have a good backup, dismount the databases and file-system defrag then.
Few related things to read:
328804 How to Defragment Exchange Databases
192185 XADM: How to Defragment with the Eseutil Utility (Eseutil.exe)
256352 Online Defragmentation Does Not Reduce Size of .edb Files


Popular posts from this blog

Question كيفية عمل share للـ outlook conntact لكل الـ Domain Users

  الحل بسيط جدا عايز الكونتاكت تتحدث دايما بحيث انك لما تضيف يوزر جديد يسمع في الكونتاكت اول حاجه بتدخل علي in office 2003 tools --- email account ---- add address book --- internet directory service (LDAP) type your server name then login info . mark this server require me to logon type any user on active directory and its password then save and close outlook and open it again now you will find all your active directory users in address book

3 things has to be done for better performance

  Tips from Goutham: 3 things has to be done for better performance: By default, XP displays extra graphic objects for menu items which can slow down your display. 1. To turn off these selectively... Right click My Computer Select Properties Click Advanced tab Under Performance, click Settings button To turn them all off, select Adjust for best performance Preference is to leave them all off except for Show shadows under mouse pointer and Show window contents while dragging 2. To speed up the display of the Start Menu Items, turn off the menu shadow. Right click open area of the Desktop Select Properties Click Appearance tab Click Effects button Uncheck Show shadows under menus 3. You can increase system performance by loading more of the system into memory. DO NOT attempt this with less then 512MBs of ram. Your system will become unstable. Click Start Click Run Enter regedit Click OK Go to HKEY_LOCAL_MACHINE SYSTEM CurrentControlSet Control Session Manager Memory Management Double cli

The difference between DNS and NDS

  Novell Directory Services(NDS) - Novell Directory Services (NDS) is a popular software product for managing access to computer resources and keeping track of the users of a  network , such as a company's  intranet , from a single point of administration. Using NDS, a network administrator can set up and control a  database  of users and manage them using a  directory  with an easy-to-use graphical user interface ( GUI ). Users of computers at remote locations can be added, updated, and managed centrally. Applications can be distributed electronically and maintained centrally. NDS can be installed to run under  Windows NT , Sun Microsystem's Solaris, and IBM's  OS/390  as well as under Novell's own  NetWare  so that it can be used to control a multi-platform network. NDS is generally considered an industry  benchmark  against which other products, such as Microsoft's Active Directory, must compete. Lucent Technologies plans to integrate NDS into its own QIP product