Microsoft Exchange is the Florida of Windows server applications: As goes Exchange, so goes Windows, or so it would seem. With more than 50 million client seats, Exchange/Outlook is Microsoft's major enterprise application. We can learn a lot about storage and backup from how enterprises implement Exchange.
In September, Windows 2000 Magazine polled Exchange UPDATE readers and found that their Exchange data stores are typically in the 1GB to100GB range. In addition, several respondents have really large data stores, in the multi-TB range. With the introduction of Exchange 2000'sWeb Store, which includes rich data types, most people anticipate that the size of Exchange data stores will rise sharply in the near future. Storage vendors watch this platform closely, because Exchange in particular and messaging systems in general offer near-term marketing opportunities.
Most companies consider messaging a "mission-critical" application. (According to our respondents, Exchange servers offered about 99.9 percent uptime.) When we asked Exchange administrators of mostly Windows-based networks how they currently back up their Exchange servers, they answered as follows:
- 61 percent - Hot backup
- 19 percent - Cold backup
- 10 percent - Online storage management
- 8 percent - Block-level backup
- 2 percent - LAN clusters
- 0 percent - Asynchronous replication
The study didn't define hot or cold backup, but hot backup often is defined as backup run against a live data store. Cold backup involves detaching clients from the server so that the data store is static or splitting off a mirrored volume and backing up against it. As you can see, most respondents keep their systems live during backup.
Additionally, we asked what backup software Exchange sites used and received the following results (respondents could mark all answers that applied):
- 100 percent Veritas Backup Exec
- 55 percent CA ARCserve IT
- 44 percent Windows Backup
- 19 percent Legato Networker
- 12 percent Veritas Netbackup
- 9 percent Tivoli (IBM) ADSL
- 6 percent CommVault Galaxy
- 4 percent BEI Ultrabac
One storage vendor pointed out that Microsoft's Exchange team doesn't support Network Attached Storage (NAS) for Exchange, referencing Microsoft article Q250348. According to the article, Exchange Server 4.0, Exchange Server 5.0, Exchange Server 5.5, and Exchange 2000 Server don't offer NAS support. NAS use requires a redirector and moves the data using Server Message Blocks (SMBs) that would be complex to test. The problem is even more pronounced with Exchange 2000 Server's new file system driver. (I would guess, however, that NAS using Windows 2000 Embedded might well find support at Microsoft.)
Given the storage industry's current affinity for snapshot technologies, Exchange Microsoft article Q221756, "Support Boundaries or Snap Backup and Restoration Technology," is equally interesting. The article describes using offline backups and restorations with Exchange 5.5, especially how to maintain LOG file consistency and data integrity. The article blesses EMC's Timefinder, Compaq's Restore Accelerator for Exchange Server using the Compaq SANWorks Virtual Replicator (SWVR) software, and Compaq's Uptime Booster for Microsoft Exchange.
The article also notes that some snapshot backup technologies, such as those developed for NAS devices, aren't supported. Such statements don't exactly comprise a ringing endorsement for using the NAS snapshot backup technology that companies such as Network Appliance offer.