SQL Server Performance Forum – Threads Archive
Single vs Dual Disk Array Controllers
Single vs Dual Disk Array Controllers For example, having two "identical" databases on two volumes with single controller vs assigning each database and its volume to separate disk array controller… I understand that there will be possible gains from separate disk caches etc… What kind of real world performance gains can I expect by adding another disk array controller ? Thank you.Initially when you are configuring database that will only contain a few gigabytes (GB) of data and not sustain heavy read nor write activity, it is not as important to be concerned with the subject of disk I/O and balancing of SQL Server I/O activity across hard drives for maximum performance. When it grows it is necessary to take care of write/read activity with the drive configuration around maximizing SQL Server disk I/O performance by load-balancing across multiple hard drives.
The read/write heads and associated disk arms need to move in order to find and operate on the location of the hard drive platter that SQL Server + Windows asked it to. Fyihttp://www.microsoft.com/technet/prodtechnol/sql/2000/maintain/rdbmspft.mspx Satya SKJ
Microsoft SQL Server MVP
Writer, Contributing Editor & Moderator
http://www.SQL-Server-Performance.Com
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the idea is to distribute IO load across multiple buses, controllers, & disks that is 1 controller in each PCI-E slot (in the previous generation, controllers should not be on the same PCI-X bus, but this does not apply to PCI-E for now) start with 10-15 disks on each controller if you only have 8 disks, splitting them on 2 controllers does not really help because 4 disks will not overload 1 controller
12-15 disks could fully load 1 controller in sequential ops, but not random
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