IBM R5 manual Distribute I/O Across Physical Disks, Log Performance Metrics Consistently

Lotus Domino Server R5 Implementation Guide June 18, 2001

Distribute I/O Across Physical Disks

Our experience has shown that physical and logical disk structures are our customers' least understood system resource, and the one most often undersized. The best way to boost performance on many Domino servers is to distribute I/O across separate physical disk subsystems.

Ideally, you want to put the following I/O-intensive files on separate physical disks:

ŸThe Notes paging file

ŸYour .NSF files

ŸThe Domino R5 transaction log

If you can put them on separate controllers, too, so much the better. The idea is to increase I/O throughput by distributing the work over busses, controllers, ports, and disks. Hence, several small physical disks are better than a few large-capacity disks. In particular, the more you isolate the R5 transaction log from other disk activity, the better your server performance will be.

Log Performance Metrics Consistently

If you don't log performance metrics, you won't be able to quantify the success or failure of your tuning efforts. If you do keep logs, you'll not only have a far better idea of what you're doing, you'll have a far easier time documenting the need for additional expenditures.

Among the key metrics to track are:

ŸTotal CPU utilization (expressed as a percentage). If this metric is above 70% to 80%, that's a red flag.

ŸDisk queue length (typically this should be less than 2 items in the queue) and average disk service time (should be less than 70%).

ŸPaging file size and utilization. Utilization should be fairly low, or it's probably worth it to buy more memory

ŸDomino statistics and events for mail throughput, replication, Web server activity, and database activity.

ŸDomino logs (log.nsf); they're boring but they often come in handy.

It's important to collect production data weekly, and analyze it monthly if possible. It's also critical to capture "snapshots" of performance before and after major configuration changes.

For AIX systems, there is a Notes Agent for Performance Toolbox (PTX) that will monitor and report on Domino Performance.

Optimize for Domino R5

Domino R5 does a great job auto-configuring and dynamically reconfiguring key parameters for maximum performance. Here are some tips from the experts on how to tune the Domino R5 server itself:

ŸSet up the correct number of mailboxes. Multiple mail.box files reduce contention for mail deposits and other mail-related activity. The biggest performance gains come when you add a second mailbox. The rule of thumb we use is one mailbox for 1-200 users supported, two or more for 200-1,000 and ten (the maximum) for 1,000 or more users.

ŸFor non-partitioned systems, let Domino dynamically set NSF_Buffer_Pool_Size. This is particularly important in low memory server configurations, where a large buffer pool can interfere with the kernel's memory management.

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