Step 9: Choose and optimize your disks wisely

Choosing the proper disk type, optimizing disk speed and sizing your disks for future database growth are key elements to ideal hardware performance. Learn more in this tip.

Disk type

First you should choose the highest-performing disk type you can afford for your environment. While there have been improvements in disk technologies such as iSCSI and Fibre Channel over the past several years, SCSI drives still offer the best performance. For optimal disk performance, consider solid-state RAM drives, but be prepared to pay for their superior I/O performance.

For small databases that will largely be stored in RAM, you may find that performance is insensitive to the disk type.

Disk speed

Also try to purchase the fastest disks you can, preferably Fibre Channel, which offers the greatest data transfer speed.

Ensure that all disks are rated for the same speed and they are all the same model. Different speeds or models can slow down your entire disk array through a phenomenon known as hardware impedance mismatch, where the overall speed of the disk solution will be lower than the lowest member. Currently the fastest disk speed is 15 KB.

Check out this Fast Guide to Storage Technologies for a better understanding of various disk types and storage technologies.

Disk size

When sizing your disks, they should be large enough to hold the expected size of the database files over the lifetime of your database. Consult with your developers and business customers to determine long-term growth needs.

Your disks should also be able to hold several backups and transaction log dumps. Keep in mind that most indexing processes result in large transaction logs and log dumps.

The larger your disk size is, the more insurance you buy yourself during restore operations; having a backup on disk enables faster restore times than restoring from tape or tape drive units. You must also account for some performance degradation in the event you run out of space on a drive and have to extend your database files to span multiple physical disks.

Spec your SQL Server hardware needs

 Home: Introduction
 Step 1: Invest in good application design
 Step 2: Understand your workload
 Step 3: Know your memory support limitations
 Step 4: Choose a reliable hardware brand
 Step 5: Take advantage of 64-bit
 Step 6: Take advantage of storage area networks
 Step 7: Properly configure your RAID arrays
 Step 8: Use separate disk controllers
 Step 9: Choose and optimize your disks wisely
 Step 10: Optimize CPU activity and speed
Hilary Cotter
Hilary Cotter has been involved in IT for more than 20 years as a Web and database consultant. Microsoft first awarded Cotter the Microsoft SQL Server MVP award in 2001. Cotter received his bachelor of applied science degree in mechanical engineering from the University of Toronto and studied economics at the University of Calgary and computer science at UC Berkeley. He is the author of a book on SQL Server transactional replication and is currently working on books on merge replication and Microsoft search technologies.
Copyright 2006 TechTarget

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