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Disk Alignment and Disk Formatting for Exchange

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  • Disk Alignment and Disk Formatting for Exchange

    I am a little confused on how to proceed. I want to use diskpart.exe to properly align my disks that will be used to host my Echange DBs. Some sources say to use the command DISKPART> create partition primary align=32 and some say to use the same command, but = 64 instead of 32.

    This is an iSCSI connection connecting to a RAID 10 volume on my SAN. I checked my SAN documentation and below is what is states:

    I/O alignment:
    In general MS Exchange I/Os are predominantly 4K in size. It is therefore important to ensure that these logical transaction I/Os are not split into different spindles. Splitting increases physical I/Os and therefore degrades performance. By default Windows aligns the partition to 63rd sector. This implies that one out of every 16 I/OS will be split, causing performance penalty. It is advisable to use Microsoft tool diskpart to align the volumes to 4k alignment. “diskpart –i 1” command will ensure this alignment.

    Given the above statement which increment should I use? 64 or 32?

    Lastly when I finish with Diskpart.exe and I go into the GUI Disk Management and I format the disk from there what Allocation Unit Size do I select from the drop down to ensure proper configuration with the alignment?

  • #2
    Re: Disk Alignment and Disk Formatting for Exchange

    Here's an excerpt from a Technet article:

    At the Diskpart command prompt, type Create Partition Primary Align=X, where X is either 32 or 64, depending on the recommendation from your storage vendor. If your storage vendor does not have any specific recommendations, it is recommended that you use 64.

    As for the Allocation unit size, I believe I just took the default of 4096.