Why you should align your SSD

Aligning an SSD is the process of ensuring that your filesystem’s logical blocks begin and end on the same memory boundaries as the SSD’s memory blocks. Doing this improves speed and longevity. Not doing it can roughly halve your drive’s life expectancy.

It’s not as mysterious or weird as it may seem. I’ll try to take the mystery out of it.

A traditional hard drive just writes data in chunks–whether they’re 512 bytes or 4K depends on the drive–and doesn’t care how you do it. An SSD is made up of memory cells 4K in size, and since those cells can wear out over time, an SSD does care how you do it.

Your operating system’s filesystem splits up data into chunks that are a nice, even multiple of 1K. If the filesystem’s boundaries line up with your SSD’s 4K boundaries, everything’s great. But if they don’t line up, the SSD has to write onto two 4K memory cells. How much this slows operations down depends on the SSD–with some drives, the slowdown is negligible. And even if you have a badly misaligned SSD, it will still be much faster than a platter drive, so you may not notice or care.

But here’s why you should care: It will decrease life expectancy since the drive is actually writing twice as much data as it would otherwise. This is called write amplification, if you care to know. And personally, if I pay $200 or more for a large SSD, I don’t want to do anything to it that will decrease its life expectancy. I want it to last the promised 5-10 years.

Aligning an SSD is a fairly straightforward process that shouldn’t take too long–less time than you’d spend defragmenting a traditional hard drive–and you can accomplish it entirely with software that doesn’t cost anything. See how to align your SSD or RAID array for free.

If your drive included software to clone your old drive to your new one, it may very well have aligned the drive during the cloning process. And if you installed Vista or Windows 7 fresh onto your new drive, it installed it. But under any other circumstances, there’s a good chance your drive isn’t aligned. Here’s how to check. That won’t cost you anything either.

Here’s another trick: Make sure AHCI is enabled (scroll to the end of the link). Enabling AHCI allows functionality like NCQ and TRIM to work.

4 thoughts on “Why you should align your SSD

  • August 12, 2011 at 1:12 pm
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    Last time we were talking about clonezilla etc, I finally got around to trying it, specifically for cloning a linux install. It definitely works, but the interface is one hell of a beast. Too easy to press the wrong key and kiss it all goodbye. Lots of text and no pictures. Oh well, it worked like it said it would, for the linux migration.

  • August 18, 2011 at 1:03 pm
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    Following your recent panegyrics (oops, that’s one of those portmanteau words you so despise!) on the virtues of SSDrives, I went out and bought one. It’s blank and empty.

    Now I could just clone everything and then run the alignment, but is there an easier and less disk (chip?) intensive option? Intel shipped the 510 drive with a bundled version of Acronis for cloning. I’m happy with that, and have my own I can use as well; though I’m really a Ghost guy, myself.

    I’ve got two partitions and running WinXP.

    Thanks for any tips you may have.

    • August 18, 2011 at 7:04 pm
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      Yep, just run the Acronis bundled with the Intel SSD. That version of Acronis will align the partitions before it starts cloning them, without you having to do anything else. That’s the least write-intensive option I can think of. Luckily it’s also the fastest and easiest.

  • August 21, 2011 at 12:56 am
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    Aside from having to disable almost everything under the sun before actually INSTALLING the latest version from Intel, it worked like a charm.

    I ran the new SSD through a USB adapter I use for a bulk and spare SATA drive, so that may have been the source of the installation problems. Only warning I’d give is that it didn’t really mention that the process would be completed in DOS, prior to a Windows boot. The transfer session started out looking suspiciously like a standard disk check, which I’ve been known to abort…. Glad I didn’t do that!

    I checked alignment, and it was spot on, so no need to to realign.

    Boots much faster, not nearly as hot. More later, if you want details.

    Thanks again for the tip.

    Jim`

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