Make Sure Your Partitions Are Correctly Aligned For Optimal SSD Performance

We've covered proper solid state drive maintenance before, but one of the most overlooked factors in proper SSD care is partition alignment. Here's how to make sure your partitions are aligned correctly and that you're getting the most out of your SSD.

We talked about partition alignment in our SSD migrating tutorial, but if you've already migrated to an SSD, you might not have realised that you're sacrificing performance with misaligned partitions. A regular hard drive usually starts its first partition after 63 empty blocks, while SSDs require 64 blocks of data for optimal performance. This means that sometimes, if your SSD was formatted by something other than Windows' installer, it can be aligned incorrectly and will transfer data much slower than intended.

To see if your partitions are aligned correctly, hit the Start menu and type in msinfo32. Enter Msinfo32 and go to Components > Storage > Disks. Look for your SSD on the list and find the "Partition Starting Offset" item. If this number is divisible by 4096 (that is, if dividing it by 4096 equals a whole number and not a decimal), your partition is correctly aligned. If not, you need to realign it. Luckily, this is pretty easy to do with the Gparted live CD. If you have an Ubuntu live CD lying around, that will work too, since it has Gparted available under System > Administration.

Start up Gparted and find your SSD in the upper-right dropdown menu. Select it, and click on your first partition in the menu. Hit the Resize/Move button in the toolbar. Change the "Free Space Preceding" box to 2MB, uncheck "Round to Cylinders", and hit "Resize/Move". Hit Apply once and let it do its thing.

Now hit Resize/Move again, and change the "Free Space Preceding" box to 1MB. Uncheck "Round to Cylinders" again, hit Resize/Move, then click Apply. Now your drive will be aligned to exactly 2048 blocks after the beginning of the disk, which allows for optimal SSD performance. Note that if you have multiple partitions on your SSD, you'll need to repeat this process for each partition, not just the first one on the disk.

Yes, moving it 2MB away then moving it back 1MB seems like a long, roundabout method, but Gparted measures space in a weird way. When you first start up Gparted, your partition will have less than 1MB of space preceding it, but Gparted will only measure it as 0 -- meaning if you align it to 1MB right off the bat, it'll keep the drive annoyingly misaligned at 1.03MB. If you set it to 2MB, hit Apply, and then move it back to 1MB, it works fine.

Boot back into Windows, open Msinfo32 back up, and run the above check again. If you get a whole number this time, your partition is correctly aligned. If you get an error when you try to boot back into Windows, that doesn't mean you did anything wrong -- sometimes Windows gets a little confused and can't find a partition if you move it (even if you only move it 0.7MB away). Grab your Windows installation disc, boot into it, and hit Repair Your Computer on the main menu. It should automatically detect the issue and fix your boot menu for you.

That's it. It seems a little complicated and roundabout, but it's something not a lot of people know to do, so you may have been sitting with a non-optimised SSD for all this time (I know I have been for a few months). This should fix the problem, and if you've had your SSD for awhile, you might even notice a speed boost.

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Comments

    It should also be mentioned about the benefits of using a GPT (GUID Partition Table) partitioning table over the more traditional outdated MBR (Master Boot Record) table. Not to mention the benefits it gives to your SSD's life and performance.

    One thing you should know is that Windows 7, being Windows, is not compatible with GPT, yet. Hopefully it will be standard in Windows 8. Linux supports it natively and most likely Mac OS X (check it out first). There are many guides about migrating from MBR to GPT on the net.

    Most modern operating systems install block-aligned these days with a fresh install. A simple rule is just to always align partitions to 1MB boundaries - this will ensure that you're always 4k block-aligned.

    "As SSD Benchmark" is a free (run from exe only) App that will tell you whether you have correct alignment and also tell you how fast your SSD is. The best thing to do is run it before you change anything and then run it again after. If your SSD was incorrectly aligned you will see a marked difference in speed after!

    Also if it was formatted as part of a fresh install of Windows earlier than Vista, it will be misaligned by default.

    Create your aligned partition (1024KB offset is the default in Windows 7, and is correctly aligned on a 4KB boundary), and THEN install your OS.

    I remember leaving a 1mb free space when I did this like a year and a half ago. Today I actually checked and I'm misaligned. I will have to try the 2mb to 1mb workaround.

    I used Gparted to align to 2Mb and 1Mb, but unfortunately Windows was not able to boot as a result of inaccessible device. In the end I had to restore my Acronis backup image back to the partition before booting could work. I guess Gparted in its alignment process corrupted some important data.

    After booting the restored image, i see that the partition is aligned at 1048576 bytes so hope that is all the SSD needs. thanks.

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