Repartition using DiskPart and a 1MB offset

hi all

from preliminary tests on a san to be used for SQL, we have gathered that the raid 10 config for the DB is not giving the desired I/O through put.

iv been told to Repartition using DiskPart and a 1MB offset, can anyone advise how i do this?
i have downloaded diskpart and can check the volumes etc but would appreciate advice on how to take the next step!
malraffAsked:
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TripyreCommented:
that would require a restore of your data.  Using diskpart to align the disks will erase all data.  The best thing to do is to attach another LUN/disk of the same size with the correct alignment and then copy the data to the new disk then remove the old one.

***Running Diskpart on a disk that has data will ERASE the data!!***

but the commands are as follows:

C:\>diskpart
Microsoft DiskPart version 6.0.6001
Copyright (C) 1999-2007 Microsoft Corporation.
On computer: ASPIRINGGEEK
DISKPART> list disk
  Disk ###  Status      Size     Free     Dyn  GPT
  --------  ----------  -------  -------  ---  ---
  Disk 0    Online       186 GB      0 B
  Disk 1    Online       100 GB      0 B
  Disk 2    Online       120 GB      0 B
  Disk 3    Online       150 GB   150 GB
DISKPART> select disk 3
Disk 3 is now the selected disk.
DISKPART> create partition primary align=1024
DiskPart succeeded in creating the specified partition.
DISKPART> assign letter=F
DiskPart successfully assigned the drive letter or mount point.
DISKPART> format fs=ntfs unit=64K label="MyFastDisk" nowait
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malraffAuthor Commented:
they are all blank partitions at the moment except for C which has OS,

iv been using sqliosim to stress test the drives
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malraffAuthor Commented:
used diskpart and IO request blocks seem to have went down again?
on diskpart i entered
DISKPART> select disk 3
Disk 3 is now the selected disk.
DISKPART> create partition primary align=1024
DiskPart succeeded in creating the specified partition.
DISKPART> assign letter=F
DiskPart successfully assigned the drive letter or mount point.
DISKPART> format fs=ntfs unit=64K label="SQL" nowait


Target IO Duration (ms) = 100, Running Average IO Duration (ms) = 15, Number of times IO throttled = 920, IO request blocks = 58 CLogicalFile::OutputSummary e:\yukon\sosbranch\sql\ntdbms\storeng\util\sqliosim\fileio.cpp 529
 04/15/10 16:24:58 3968 Display Monitor Reads = 12096, Scatter Reads = 28798, Writes = 509, Gather Writes = 25502, Total IO Time (ms) = 3876896
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malraffAuthor Commented:
my IO stats have actually went down after using diskpart - strange!!??
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TripyreCommented:
are you saying that your performance is better after aligning your disks or are you saying that your performance is worse?  Aligning the disks also depends on the SAN vendor.
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malraffAuthor Commented:
worse , sorry i know iv deviated from the question asked!
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malraffAuthor Commented:
maybe should i have deleted the volume first? then setup from scratch using diskpart?
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TripyreCommented:
give that a try.  But consult with SAN vendor on their offset for disk alignment.
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JustenCCommented:
Yes 1024 isnt quite it, it has to be a multiple of 4kb.  I recommend offset at 32kb for local, I know EMC requires 64 because of the way they split IO across disks. So "create partition primary align=32" for example.

I apologize in advance for any duplicate posts by our proxy server

Justen
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JustenCCommented:
Yes 1024 isnt quite it, it has to be a multiple of 4kb.  I recommend offset at 32kb for local, I know EMC requires 64 because of the way they split IO across disks. So "create partition primary align=32" for example.

I apologize in advance for any duplicate posts by our proxy server

Justen
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malraffAuthor Commented:
Hi justin , I will try your suggestion 2 morow. It also does happen to be an emc San
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JustenCCommented:
Good deal just remember do not put in align=64000 or whatever just align=64, the kb part is already understood.

I apologize in advance for any duplicate posts by our proxy server

Justen
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JustenCCommented:
Good deal just remember do not put in align=64000 or whatever just align=64, the kb part is already understood.

I apologize in advance for any duplicate posts by our proxy server

Justen
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malraffAuthor Commented:
hey justin
 can i really expect the stats to improve drastically with this configured properly?

also what do u recomend to set the queue depth at? it currently is at 32 and the IO request blocks for 6 discs is only 58! so low its strange!
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JustenCCommented:
yes it should be fairly dramatic. 'Split I/O's' cause a big performance hit. Microsoft always refers to it when they check our big SQL configs as well.

Queue depth on the HBA? EMC has formulas that depend on the number of hosts on the SP, the Flare code version if it's a Clariion, etc. You're best asking them or checking Powerlink.
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JustenCCommented:
yes it should be fairly dramatic. 'Split I/O's' cause a big performance hit. Microsoft always refers to it when they check our big SQL configs as well.

Queue depth on the HBA? EMC has formulas that depend on the number of hosts on the SP, the Flare code version if it's a Clariion, etc. You're best asking them or checking Powerlink.
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malraffAuthor Commented:
It's an iscsi San I'll try diskpart again first tho
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