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What scheduled maintenance, tasks or jobs should be performed on Exchange Server and how often?

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up vote 3 down vote accepted

Some people might say that you should perform an offline defragmentation of the IS on some schedule. I've seen E2K3 machines go years without ever having an offline defragmentation, so it's not a requirement for continued operation. Likewise, I've heard people swear by performing a fileystem defragentation of the volume holding stores with the database engine shutdown (assuming the filesystem is on DASD and not a SAN volume). I've also seen E2K3 servers run for years (with acceptable performance) having never had this done either.

The main recurring job that's necessary is a regular online backup. By default, E2K3 runs its database engine in a non-circular logging mode, so transaction logs are going to pile up until a full or incremental online backup is run. As such, you should be doing regular online backups.

Everything else is either automatic (IS maintenance) or can be schedule to run during production (address list rebuilds, mailbox manager policies).

I'd love to hear others' thoughts on this, though.

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I'm in agreement. In my opinion there should be only 2 scheduled maintenance "plans" on an Exchange server. #1 - online backups. #2 - OS/Exchange critical/security updates. The second should be done after you understand the implications of the patches and (IMO) let them be in the wild for a few weeks at least. Of course, do #2 after a full backup. I'm one of those that thinks that an Exchange server runs best if you don't touch it (other than above). – TheCleaner Jul 2 '09 at 13:22
+1 All the documentation i have every read states that offline defrags are NOT ment to be a regular task, but for situations where the online defrag isn't cutting it for some reason or you have some other issue with your exchange database. – Zypher Jul 2 '09 at 19:42

I would tend to agree with Evan on this. We survive without doing regular maintenance or defrags at all.

The only thing I would say, is that if you delete accounts, you do not reclaim their mailbox space unless you do an offline defrag. At least, that is my understanding and I would love to be proved wrong on this one.

I think in a lot of organisations, maintenance on exch 2003 stuff tends to be left until its necessary, ie to fix corrupt message db's etc.

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Backups and patches are key. Integrity check and Defrag are, IMHO a best practice, especially as your Exchange DB grows above 50GB.

Integrity checks assist in ensuring no corruption. The Defrag reclaims (possibly precious) disk space -- not trivial, especially if you are in a company with a high turnover rate.

The problems with Integ and Defrag is the time they take to complete, and for the defrag, the disk space needed to run. You actually need empty disk space equal to 1.2x your current Exchange DB size to defrag.

I have had the integ/defrag combo take anywhere from 6hrs (20GB) to 22hrs (90GB) on 15KRPM U320 disks. Just painful, and in some instances impossible.

Another option to "defrag", though hokey, is to create an additional Mailbox store, and migrate users over. Then delete the old Information Store once empty.

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I'd question letting a store get to be 50GB+ in size (at least on E2K3). At that point, you may be running afoul with SLA's for restores anyway. (If it's a standard edition / enterprise edition type question at that point then I'd say "bite the bullet and go to E2K7".) The "move the mailboxes to another store" technique actually sounds like a rather ingenious solution, though you're going to lose single-instance storage when you do that. – Evan Anderson Jul 2 '09 at 20:24
Agreed Evan, however sometimes you have no choice. Small company -- 50 people, and management refuses to allow you to apply mailbox limits. Add to that file server space is 90% full (so archiving is not a reasonable request, except to DVDs) and spending halted/cut. Sometimes there really is no choice at all..... :-) – Scott the I.T. Guy Jul 6 '09 at 13:30

Actually, backup software sets the archive bit, to show that has been archived or backed up. You can open a file with the A bit set over and over again and it will not change anything. However, if you modify any file and save it, the operating system will reset the A bit. If you do a full backup, it copies or backs up everything, regardless of the A bit status.

But the magic of the archive bit is when you do an incremental or differential backup, it will only back up the files that have the A bit cleared (meaning it needs to be archived). After the incremental backup, the A bit will be set again by the backup software. It's just an efficient way for the backup software to let the OS and user know what a file has been backed up, and an efficient way for the OS and user to let the backup software know that a file has been changed. The difference between incremental and differential backup is whether they look externally to when the last backup (incremental) or internally to when the last full backup (differential) happened for a new archive set.

Let's say you have 1000 files backed up on Sun, and modify a different set of 100 files every day, and need to rebuild a system on Fri morning. With incremental, you will have to restore 1 Full backup tape(s) and 4 incremental (Mon's 100, Tue's 100, Wed's 100, Thu's 100) tapes in order to have a full system again. With differential, you would have to restore 1 full tape and Thu's differential (400 files). Differential is easy (full plus differential = DONE), but requires more backup storage (100+200+300+400+500, while Incremental is fast and cheap, but requires more complexity during the restore process (and risk--what happens if Wed's tape is missing?).

The driving forces are usually how many tapes you have, how much data you have and need to back up on a daily basis, and how much of a backup window you have. Most people try to go with full and differential, if they can afford the backup storage (tape or disk), because it's easiest. Some people are forced to go with daily incremental, but don't have a lot of duplication on their incremental tapes like they would on the differential tapes.

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