Sunday, December 6, 2009

Windows 7 on SSD - how to create an aligned partition for best performance


  How to restore an image with Acronis True Image and keep the partition alignment

Several benchmarks have shown that having an aligned partition on a SSD hard drive will result in better performance (20-50%).
But if you are using Acronis True Image and want to restore an image for some reason, you could loose this precious alignment since True Image could delete the partition first and recreate it unaligned before restoring the data.
I will describe the steps to prevent this.

First I will show the steps for creating an aligned partition before installing Windows 7.
  • boot Windows 7 from the install DVD or a USB pen drive (How to prepare a USB pen drive for installing Windows 7)
  • select language, then "Next"
  • select "Repair your computer"
  • check "Use recovery tools that..", then "Next"
  • select "Command Prompt"
  • diskpart
  • list disk
  • select disk 0
  • clean
  • create partition primary size=32768 align=1024 (size is just an example, this will create a 32 GB partition for C: to install Windows 7 on)
  • create partition primary align=1024 (second partition D:, it will take the rest of the space of hard disk 1)
  • select partition 1
  • active
  • list partition
  • exit
  • close command prompt window
  • continue to install Windows 7 on the newly createted partition (C:)
Important thing here is the parameter align=.., I would recommend the number 1024 to have this partition aligned on a 1024 KByte border (2048 sectors), this should be good choice for any SSD currently available.
(There are SSDs which need at least a 128 KByte alignment, others will need a 512 KByte alignment for best performance. So with a 1024 KByte alignment you will be on the safe side.)

Now if you want to restore the Windows 7 system partition C: from an Acronis image, follow these steps:

  • boot Acronis True Image from a Rescue CD or a USB pen drive
  • select Restore
  • select the source image (C:) you created earlier and want to restore, either from partition D: etc. or an external USB hard disk (must be present when you boot the Acronis rescue media)
  • select the destination: partition 1 / 32 GB (this is our aligned partition)
  • select only NTFS/Volume C:, not MBR/Track0
  • verify the Acronis options: new location(C:), primary, mark as active
  • restore it
This will keep the alignment of the restored partition, it was tested with Arconis True Image Home 2010, Build 6053.

How to verify if the partition is still aligned after Acronis True Image did the restore:

You can do the verification either with Microsoft's command line tool diskpar, this will require some math to calculate the alignment.

Or get a copy of Argus Monitor (the trial version will do), go to the SMART section and select the hard drive you want to check.
Next open the drive information window, scroll to the bottom of that window and you will see the partitions for that drive as well as the alignment of each partition.


  1. This results in an aligned partition on the SSD, but it won't necessarily boot. (If the SSD previously had a good MBR, it MIGHT boot).

    Try something like MBRWizard ( to fix the problem.

  2. Four questions and a comment. If this is a new SSD, and you don't copy the MBR over how is it supposed to boot?. Why do you say to "select only NTFS/Volume C:, not MBR/Track0"? Will that mess with the alignment?. Does this work with the Acronis disk clone utility? The comment is that MBRWizard was last updated in 2005, and it doesn't mention Windows 7 support.

  3. What about Windows 7's 100MB boot partition? My Ultimate build creates a disk with two partitions, one 100MB as the first. This system ignores that stage.

  4. Wow a clear procedure at last. Thanks you very much.

  5. @Anonymous April 20, 2010:
    - the article focuses on restoring a partition, so the MBR is already there from the previous Windows 7 installation
    - if you select only Volume C:, it will not mess up the alignment
    - it was only tested with the restoration feature of Acronis True Image

  6. So what I did to get the same results was make a BESR 2010 backup of my C: drive. Then I put the SSD in and installed a clean install of Windows 7, which creates the proper 100MB partition to align the drive. Once the install was complete, I restored the BESR2010 backup image to my new aligned C: drive.

    After this, the system would not boot. So I put the Win7 install CD into the drive and booted to it. I did a repair. Windows said it was attempting to repair and may need to repeat this step a second time. After the first repair, I still could not boot from the SSD. So I did the repair again, and it did something different. After that, the system booted to a restored Win7 install on an aligned SSD.

    Not too difficult, but hard to figure out for the layman. I used this blog to guide me. I just deviated and let Windows 7 do the alignment.