Comments on: How much performance are you loosing by not aligning your drives? http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/ Tue, 07 May 2013 13:39:52 +0000 hourly 1 By: Mrdenny http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-98 Mrdenny Mon, 15 Sep 2008 19:12:30 +0000 http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-98 John,
I forgot to mention if you happen to be going to PDC in Los Angeles this October, we are having a [A href="http://www.socalcodecamp.com"]Code Camp[/A] the weekend before. At the code camp I’ll be giving a session on [A href="http://www.socalcodecamp.com/session.aspx?sid=76cc1740-42b5-4298-9bd4-856eb9872294"]Storage for the DBA[/A] which you may find interesting.

Denny

]]> By: Mrdenny http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-97 Mrdenny Mon, 15 Sep 2008 19:10:09 +0000 http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-97 John,
Sorry it took me so long to get back to you. Its been a busy couple of weeks.

1. The OS defaults to 32KB because when the fat file system was defined space was an issue and every 32KB counted. These days that lost 32KB isn’t a problem, but it causes the alignment problem which then causes performance problems.

2. Actually all disks which store data which is frequently accessed should be aligned. This includes database servers, file servers, exchange servers, etc.

The Disk Sector Size and Stripe Unit size will be gotten from the storage it self. When working with SQL Server its best to set these to 64KB as SQL Server does everything in 64KB chunks.

]]> By: JohnMCouch http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-93 JohnMCouch Tue, 09 Sep 2008 20:44:16 +0000 http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-93 I read a bit from this Microsoft article in relation to aligning the partitions but I don’t fully understand where to get these values or determine I am aligned correctly. It states in the article that in order to determine when alignment occurs, you need the below formula:

((Partition offset) * (Disk sector size)) / (Stripe unit size)

Partition Offset is found in Diskpart as you show above. How do you determine Disk Sector Size and Stripe Unit Size?

http://support.microsoft.com/kb/929491

Thanks in advance for your help.

]]> By: JohnMCouch http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-92 JohnMCouch Tue, 09 Sep 2008 19:11:53 +0000 http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-92 That is very interesting. I have a couple of questions though in reference to this.

1: The operating system is defaulted to 32KB because of the waste that would occur for storing data that is smaller than 64KB. Is that correct?

2: Based on answer above, is it my understanding that only the drives where you would store SQL Server Database Data/Log Files should be aligned?

]]> By: Mrdenny http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-65 Mrdenny Thu, 26 Jun 2008 19:15:34 +0000 http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-65 You use the diskpart command to see the partition offset.

Open a command prompt and select the disk you want to see. Then type “list partition” and look at the offset. You are looking for a 64k offset, the default is 32k.

]]> By: Shel http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-64 Shel Wed, 25 Jun 2008 14:15:37 +0000 http://itknowledgeexchange.techtarget.com/sql-server/how-much-performance-are-you-loosing-by-not-aligning-your-drives/#comment-64 interesting stuff, Denny. This is my third week at a new job. Is there a way to identify how our servers are configured?

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