Misaligned partitions - how can I fix this?

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daws0n

Weaksauce
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Feb 26, 2005
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I've just installed a new 40GB Intel SSD, looking into setting them up it's brought to my attention the issue of misaligned partitions. Using the correct procedures, I sucessfully have Windows 7 running on my SSD with 4096 per allocation unit and a 1024KB partition starting offset.

While checking this with diskpart, I thought I'd take a looking at my 1TB mechanical drive's partition arrangement. This was set up using Windows XP a while ago, and something's not quite right:


Partition ### Type Size Offset
------------- ---------------- ------- -------
Partition 1 Primary 29 GB 31 KB
Partition 0 Extended 872 GB 29 GB
Partition 3 Logical 872 GB 29 GB
Partition 2 Primary 29 GB 902 GB

The fact that my main partition is logical doesn't bother me, but the offsets look way way off. Short of re-partitioning and restoring my data, is there anyway I can fix this? In it's current state, is my configuration taking a performance hit?

Thanks,
Dawson
 
Last edited:
daws0n said:
I've just installed a new 40GB Intel SSD, looking into setting them up it's brought to my attention the issue of misaligned partitions. Using the correct procedures, I sucessfully have Windows 7 running on my SSD with 4096 per allocation unit and a 1024KB partition starting offset.

While checking this with diskpart, I thought I'd take a looking at my 1TB mechanical drive's partition arrangement. This was set up using Windows XP a while ago, and something's not quite right:


Partition ### Type Size Offset
------------- ---------------- ------- -------
Partition 1 Primary 29 GB 31 KB
Partition 0 Extended 872 GB 29 GB
Partition 3 Logical 872 GB 29 GB
Partition 2 Primary 29 GB 902 GB

The fact that my main partition is logical doesn't bother me, but the offsets look way way off. Short of re-partitioning and restoring my data, is there anyway I can fix this? In it's current state, is my configuration taking a performance hit?

Thanks,
Dawson
Click to expand...

Is there a performance hit? Yes (albeit minimal).
If you correct it, will you notice a difference? No

Just leave it alone.
 
Fair enough - it's not something I'm worried about unless it's slowing things down a lot. I've heard too many horror stories when people mess with partition configurations...
 
daws0n said:
I've just installed a new 40GB Intel SSD, looking into setting them up it's brought to my attention the issue of misaligned partitions. Using the correct procedures, I sucessfully have Windows 7 running on my SSD with 4096 per allocation unit and a 1024KB partition starting offset.
Click to expand...

What correct procedures are you referring to? If you do a fresh install of Win7 onto an SSD, it should provide the correct alignment. Or did you drop an image of an existing installation onto the SSD and align it afterwards?
 
Originally, I had Windows 7 running on the (mis-aligned) 1TB HDD. I create an image of my O/S partition using Norton Ghost 2003, and then installed the SDD drive along side my existing one. I partitioned/quick formatted it using the Computer Management applet, specifying the default 4096 cluster size. I then checked the drive's state using diskpart, which reported it has an offset of 1024KB.

So, if you set it up in Windows beforehand it's pretty much done for you. I then boot ghost from a USB stick and restored the image of Windows 7 to the new SSD. This failed to boot (as I expected) and I had to run the Windows 7 O/S disc and run a startup fix/repair to make a few changes to the boot manager/MBR. Took about 5 minutes, and all is running fine :)
 
Well, not really but maybe sorta kinda. :D I already have 7 installed, but as you know there are programs that break the alignment when an image is restored while others keep it intact. In the event that I have to clone my disk or move partitions around, it's good to know what people are doing to preserve (or fix) alignment. I had never even considered partition alignment until SSDs -- I guess it was always present but just not something to worry about until now.
 
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