Exchange storage and compaction

As Ed pointed out, Jack Dausman has a couple of articles about Exchange storage, and I finally have cycles to respond.

First, I find it a little sad that there’s so much effort being expended to help Chris Bordeleau tune his Domino server in the absence of any real data. Where are Domino’s performance monitoring and load testing tools? Are there no equivalents to jetstress and loadsim? Surely if Chris could post some actual performance data values the folks at Ed’s place would be able to help him out more directly.

Now, on to Jack’s postings. The Storage Magazine article he cites is, sad to say, old news to experienced Exchange administrators: using an archiving tool against Exchange won’t shrink the database unless you compact it. There are relatively few reasons why you’d actually do a compaction in practice, though:

  • you move a lot of mailboxes from one database to another, thus reducing the amount of data needed for the source database
  • you do a first run of an archiving / vaulting tool that removes a significant amount of message data
  • you’re running so low on disk space that you need to reclaim white space, even though you know the store will grow again.

You certainly don’t need to run a tool like GOexchange regularly, as I’ve said before. Most sites don’t ever need to run it at all; after all, there are very few companies where the amount of stored e-mail is shrinking (don’t I wish!)

As to a couple of Jack’s other points:

  • He says that Domino supports larger mail files than other systems. I think we’re having a semantic disconnect here: Exchange supports very, very large mailbox databases, but it’s uncommon to see individual mailboxes much larger than 6 GB or so. That’s not because of any hard-coded limit; it’s mostly because of poor client performance with older versions of Outlook. The big killer here is actually the number of items, not the mailbox size.
  • He mentions turning off transactional logging to increase performance on Domino servers. Exchange doesn’t let you turn off transaction logging for the simple reason that it’s a key DR capability. I’m not sure under what circumstances it would make sense to trade off a small speed boost for degrading your DR capability.

Jack and Charles Robinson represent (IMHO) the best of the Domino community: they deal in technical discussions, not infantile bashing, and they understand their chosen products well enough to have intelligent discussions about them.

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