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Partition alignment w/ GPT partitions Expand / Collapse
Posted Thursday, March 3, 2011 10:41 AM
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I'm new here about a month and have been looking through the environment to correct some performance issues. I've come across this and I'm not sure how to read this. The question is, are these partitions aligned or not?
The server info is:
Windows 2008 R2 Enterprise Active/ Passive cluster
SQL 2008 R2 Enterprise
SAN attached for the L & M drives.
The drives I am questioning are SAN attached.
The drive partitions are also GPT partitions, NOT MBR.
I have read that the partitions in Windows 2008 and above now come aligned correctly and the GPT(Guid Partition Table) partitions round to sector alignment, unlike MBR partitions that round to cylinder alignment. But my starting offsets still add up to a number that is not evenly divisible by 64KB. This is what I'm seeing, any help is appreciated.

DISKPART> list partition

Partition ### Type Size Offset
------------- ---------------- ------- -------
Partition 1 Reserved 128 MB 17 KB
Partition 2 Primary 24 GB 129 MB


Post #1072721
Posted Tuesday, April 16, 2013 6:33 PM
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I have battled with the same question for a while here. You did not give the exact offset that you are getting, nor the SAN Vendor.

If NetApp, I will suggest you read up on:

a) How to diagnose misaligned I/O on Windows hosts

In Windows, click Start > Run > then enter msinfo32.exe to run System Information.
Select Components > Storage > Disks. Scroll to the bottom and you will see the Partition Starting Offset information. This number should be 65535 bytes for LUNs smaller than 4GB or 1048576 bytes for LUNs that are 4GB or larger.

Also, consider issuing :

fsutil fsinfo ntfsinfo <logical-drive>

and check on the "Bytes per Cluster".

and wmic partition get BlockSize, StartingOffset, Name
Post #1443059
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