Leadership By Numbers

About a year ago, I was in charge of migrating an Exchange 2000 server to Domino (RHEL). We did an migration in which the original Exchange server was converted into the Domino server, so I had the unique experience of using the exact hardware for the Domino server that had originally hosted the Exchange server—same accounts, same databases.

I probably should have taken better notes, but anyone who's done a mail migration will tell you that you want to stay in the transition window for as short of a time as possible. Two things surprised me: (1) the CPU utilization was dramatically lower for the Domino server, and (2) the data storage was a little bit smaller.

The Lower CPU usage I can explain in terms of the code rewrite for Domino 7, but using less disk space was completely unexpected. After all, I have always heard that the single-store architecture of Exchange provided the benefit of reducing disk resources (and, Domino has a single-store option as well for the same reasons). Since that migration, I've been more aware of Exchange's unique disk characteristics. This month, Storage magazine has published an article on Exchange and archiving and it raised my eyebrows when I learned that archiving doesn't do as much as I thought to recover any diskspace. On paper, "yes," in reality, "no."

Tim Tiches, director of product management for CA's Message Manager (formerly iLumin Assentor), concurs. "We will stub messages to reduce the footprint, in theory, on the Exchange server," says Tiches, "but the actual space isn't recovered until it's compacted. . . . Those newly vacated areas of the database are referred to as "white space" and may be filled with new messages. "It can get overwritten if everything's lined up perfectly," says Werelius, "but if you talk to companies that really run Exchange--whether it's 5.5 or 2003--they'll tell you, 'No, my database still grows.'"

For a Domino administrator, the above quote may seem odd, because we simply run the compactor task to recover the data released from archiving. Doesn't Exchange have a compact task? Yes and no. For Exchange, the mail service has to be taken off-line for compaction:

Besides shutting down mail service, bringing down Exchange to compact the database is an uncertain proposition because an admin won't know exactly how long it will take. "You can't really predict," says Devine, Millimet & Branch's DuBois. "You can only guess-timate."

Perhaps Exchange 2007 will fix the compact issue, but Microsoft hasn't committed to any further feature changes for the upcoming release. Troy Werelious, CEO of Lucid8, a provider of Exchange utilities, says he isn't “isn't as optimistic about Microsoft's efforts because he thinks those improvements are linked to Microsoft replacing the Jet database at the heart of Exchange's mail store. "Microsoft's most recent statement is that their goal is to be off of it by 2012," notes Werelius.

Ouch.