Wednesday, March 28, 2012

I/O Queue Length

Running transactional replication, dedicated server for distributor. While performance in terms of latency is excellent (usually 1 sec, almost never higher than 4) the disk queue length on the distributor is extremely high (over 6 usually). Is this typical? On any other server I would be very concerned, but cpu and memory usage are excellent and as said, latency is good. what is recommended config for distributor? others see high queue length?

Possibly. How many disks are part of the array which your distribution database is on?

You have to multiply the queue by the number of spindles which form your array. So if you have 5 disks in your raid 5 array anything beyond a disk queue length of 10 is a danger area.

Currently on one of my main distributors my queue length is pushing 80 - raid 5 (5 disks).|||

Thanks Hillary. ha ha i just found something out (just inherited this by the way) ... straight mirrored sets. no raid config. only thing on server is system dbs, but still...wow. at least logs are on seperate physical set.

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