Thursday, October 19, 2006

How is your NSF Buffer Pool? (SnTT)

The other week I decided to check into my NSF Buffer Pool settings - specifically the percent of database reads in the buffer pool. The buffer pool is a shared memory space that you can control on your Domino server. The "trick" is to have the "PercentReadsInBuffer" greater than 95%. If it is less than 95%, you may want to tweak the NSF_Buffer_Pool_Size_MB notes.ini value. This can take some time to achieve a good ratio. If your Buffer Pool is too high, then you're wasting system memory that can be better used for other tasks. If it's too low, then you might be able to increase it to find a good value so that a higher percentage of the reads are in the buffer pool.

IBM only recommends changing this on partitioned servers since you are sharing the memory. Most of the buffer pool information revolves around R5. Part of the reason for having this setting was that (ahem) "certain platforms" had low numbers for the maximum server memory. The buffer pool would let you allocate a specific amount for this Domino process. I think I set all of my servers buffer pools late last year and haven't touched them or really looked at the performance, so I was happy when I saw my PercentReads numbers! The old defaults were 300MB if you didn't change the buffer pool size. After having tweaked some of my servers, it turned out that 300 was a pretty good number for me. And Sametime servers can actually have a really low buffer pool setting since they normally aren't opening a lot of NSFs. Here are mine - how are yours?

Issue the following command from your server console: show stat database.database.b*

Production Mail Server: 450MB Buffer - 99.81% reads in buffer!
Production App Server: 300MB Buffer - 96.33% reads in buffer
Production IM Server: 50MB Buffer - 96.34% reads in buffer
Cluster Mail Server: 360MB Buffer - 98.44% reads in buffer
Cluster App Server: 300MB Buffer - 97.6% reads in buffer

Now Playing: "See No Evil" by Holy Soldier


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