Why should you use Diskpar (Diskpart in W2003 SP1)?

re: Why should you use Diskpar (Diskpart in W2003 SP1)?

Bernt — Wed, 10 Aug 2005 23:50:09 GMT

I’ve been wondering why there wasn’t a (native) diskpar.exe tool for Windows Server 2003. Didn’t know that it was implemented in diskpart.exe (in Windows Server 2003 Service pack 1). Great!!!

... now I just need a SAN to test it on

re: Why should you use Diskpar (Diskpart in W2003 SP1)?

Brian Hoyt — Thu, 11 Aug 2005 02:18:11 GMT

Is there a command in Diskpart similar to -i in diskpar to check the geometry of an exisiting partition? I think I created it properly but I would like to check. Or is there some other way to do it?

re: Why should you use Diskpar (Diskpart in W2003 SP1)?

Jackie — Thu, 11 Aug 2005 10:00:55 GMT

You mentioned that Exchange Server I/O is random 4 KB read & write to the database .edb file. what is the KB read & write to .stm and .log? what should the allocation unit size be set for log drive and separate LUN for "backup to disk" purpose?

Thanks!

Diskpar a jeho v

Martin Pavlis - pavlis.net — Thu, 11 Aug 2005 10:13:48 GMT

Obtaining diskpar

Robert Baron — Thu, 11 Aug 2005 15:32:48 GMT

FYI: You can get the old diskpar from the Win 2000 Server Resource Kit (or Google it). Note that the the diskpart (with the "t") included with Win2k3 pre-SP1 did not support this track alignment capability, and you had to use the old diskpar from the resource kit... we've been waiting for the new version for a long time now!

Exchange Q

Cluster Help — Thu, 11 Aug 2005 19:04:14 GMT

Exchange Q

Cluster Help — Thu, 11 Aug 2005 19:14:34 GMT

Exchange Q

Cluster Help — Thu, 11 Aug 2005 19:34:27 GMT

re: Why should you use Diskpar (Diskpart in W2003 SP1)?

Robert Quimbey — Thu, 11 Aug 2005 20:59:08 GMT

Bryan Hoyt <is there a way to check w/o diskpar in diskpart after partition creation?>

When I use Diskpart to Show partition, it says the Offset is 32KB, when diskpar shows 32256. When I use diskpar or diskpart to make a proper 32768 offset, diskpar shows 32768, and diskpart still shows 32KB. Until I hear differently, I always doublecheck with diskpar on volumes I'm not sure of. On volumes I used DISKPART.EXE to create with a 32KB offset, I am confident they are correct.

Jackie - <KB read/write to stm/log. What should Allocation Unit Size be for those and the Backup Lun>

Jackie, it is Exchange best practice to keep the STM/EDB on the same LUN. The STM size varies but averages about 8kb in production. The log writes vary in size from 512b to the log buffer size. You will want to make sure that the starting offset is multiple of 4kb. Most vendors want 32kb, some 64kb. As for Allocation Unit Size, we have always recommended the default, 4kb.

Exchange Q

Cluster Help — Fri, 12 Aug 2005 00:06:41 GMT

Why You Should Use Diskpar

Technically Speaking — Fri, 12 Aug 2005 03:43:28 GMT

Weekend reading

subject: exchange — Fri, 12 Aug 2005 17:57:44 GMT

Weekend reading

subject: exchange — Fri, 12 Aug 2005 18:16:05 GMT

Spelling mistake in Diskpar

Tim Ault — Sat, 13 Aug 2005 00:38:05 GMT

You might want to check the spelling in in the compiled utility. "Information" is spelled wrong.

Windows, Exchange, LCS, SMS, Misc.

Windows Server Clustering — Sat, 13 Aug 2005 01:02:46 GMT

Using Diskpar(t) for alignment

Dutch Partner Technology Specialists Blog — Mon, 15 Aug 2005 08:35:38 GMT

The Exchange team posted a good article just the other day about how disk alignment affects the performance...

re: Why should you use Diskpar (Diskpart in W2003 SP1)?

Rod Gilmour — Fri, 19 Aug 2005 15:40:55 GMT

With the use of virtualisation of disks in high-end SANs, eg IBM SVC, Veritas Volume Manager). Is there any advantage in sector alignment due to the disks being virtualised?

re: Why should you use Diskpar (Diskpart in W2003 SP1)?

Robert Quimbey — Fri, 19 Aug 2005 23:23:19 GMT

Rod - <...virtualisation of disks...Is there any advantage in sector alignment due to the disks being virtualised?>

Rod,
The short answer is yes, but check with your storage vendor.

Even with virtualization there are issues with alignment in cache and on the physical disks. Some storage vendors require that all LUNs presented from the san be aligned. Some see perf wins on a per LUN basis, and some see cache utilization wins. I don't have any experience with Veritas, but can say you should align on Xiotech, EMC Symmetrix, HP-EVA/XP, and HDS storage. They each have slightly different recommendations but my default 4KB boundary rule of thumb is a good start.

re: Why should you use Diskpar (Diskpart in W2003 SP1)?

Robert Quimbey — Fri, 19 Aug 2005 23:31:39 GMT

Will you see a 1%, 5%, 10%, x% improvement with alignment? If you are able to isolate some of the spindles of the SAN, and perform a test when it won't impact mission critical services, it is always best to test and see.

Unfortunately, few administrators have the luxury of planning for, or hearing about alignment before the storage has partitions. To backup, wipe, recreate partitions with diskpar(t), and then restore is...painful.

So I personally recommend you test and see. If the performance win is x% more IOs, then you will be in a more informed position to decide whether it is then worth the effort to align all of your partitions. On new storage, without a doubt, ALIGN YOUR STORAGE.

A _great_ tool that Exchange has made, Jetstress, makes it very easy, and quick to see how many IO's your database LUNs can sustain. Run Jetstress on a database LUN, delete the partition, align it, then rerun the test with a backup of that database on the now aligned partition. It should take less than 5hrs to run both tests.

Jetstress: http://www.microsoft.com/downloads/details.aspx?familyid=94b9810b-670e-433a-b5ef-b47054595e9c&displaylang=en

re: Why should you use Diskpar (Diskpart in W2003 SP1)?

Frank Carius — Sun, 28 Aug 2005 00:00:56 GMT

Great explanation. Fortunaly i had an information from EMC about these details.

Here is onemore link http://www.emc.com/pdf/techlib/H959_clariion_bu_stor_ms_exch_snapview_ldv.pdf page 18

BTW:Can you ask the programmer to correct the typo "StatringOffset" :-)

Frank

re: Why should you use Diskpar (Diskpart in W2003 SP1)?

Darth — Fri, 09 Sep 2005 16:54:30 GMT

Hi,
In this technet article it says Create Partition Primary Align=X, where X is either 64 or 128. I noticed you used the value of 32 instead. Does it matter which value is the best to use?

http://www.microsoft.com/technet/prodtechnol/exchange/guides/StoragePerformance/0e24eb22-fbd5-4536-9cb4-2bd8e98806e7.mspx

re: Why should you use Diskpar (Diskpart in W2003 SP1)?

Robert Quimbey — Fri, 09 Sep 2005 19:58:49 GMT

Darth: align=32/64/128???

Darth,
By default the gui will usually select a starting offset slightly smaller than 32kb. I choose 32kb as an example, because it fixes the core alignment issue. However, there are other factors, including cache usage, and the vendor will suggest the most optimal value. Many vendors suggest 64KB, and I've started hearing from folks in the field that some of the largest enterprise SANs are suggesting 128KB. Bottom line, Check with your vendor, and/or do a jetstress test and find out for yourself which is best.
Thanks, Robert