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I recently cloned my windows installation to a new SSD, the partition on my old hard drive was 111 GB whereas my new SSD is 120 GB. I used paragon Paragon Migrate OS to SSD and told it to use the whole drive when cloning.

It appears that the clone did not work correctly as my the partition I am using now is 111 GB and not the 120 I had expected.

Both windows disk manager and Gparted report the maximum size of the drive to be 111GB.

The model of the SSD is a Kingston Hyper X 3K.

Where could this missing drive capacity be?

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3 Answers

up vote 3 down vote accepted

Does Disk Manager show free space on the drive?

Probably 111 GB is the usable capacity of the SSD, some blocks are reserved to help with the wear leveling and write combining algorithms and for use as replacement blocks as some wear out.

I suggest you read the wikipedia article on write amplification for an explanation of why spare blocks ("overprovisioning") are needed to get good performance.


EDIT: 111 GiB == 120 GB, you are comparing the sales literature, listed in powers of 10, against your partition tool listing things in powers of 2. The wikipedia article mentioned that also.

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Disk manager shows no UNALLOCATED space. It does however have free space in the partitions. If my SSD is over-pprovisioning. Is 9GB an expected value? It seems a large enough that the manufacturer should have advertised the drive at a lower capacity. –  VBwhatnow Jun 23 '12 at 13:31
    
Also, is there any way to actually confirm that over provisioning is what's causing my problem? –  VBwhatnow Jun 23 '12 at 13:34
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@VBwhatnow: There is no problem, except your expectations based on misleading advertising, and your partition tool showing you powers of 2, not powers of 10. Technical people know that your drive actually has 128GiB of flash memory, and a sizeable chunk is used for overprovisioning. The drive was sold as 120GB because it has really close to 120,000,000,000 bytes usable capacity. I have a "128GB" Crucial C300 drive that has 119.24GB usable, which is just about 128,000,000,000 bytes. –  Ben Voigt Jun 23 '12 at 16:29
    
Both my drive and yours have equal amounts of flash, mine has less overprovisioning which means its useful life will be shorter. –  Ben Voigt Jun 23 '12 at 16:30
    
Reserved blocks are never counted towards capacity (sales literature or otherwise) because they're not available for use until there's a failure of another block (ie: 'Reserved' until needed). –  techie007 Jun 23 '12 at 18:28
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The manufacture using 1KB=1000 bytes---> 1GB=10^9 bytes

But your operation system using 1KB=2^10=1024bytes --> 1GB=2^30 = 1073741824 bytes

The actual bytes are 120GB=120*10^9 bytes according to the manufacture.

When it's showing on the OS, 120*10^9 (bytes) / 1073741824 (OS's bytes per GB)= 111.75 GB

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My 120 GB Corsiar SSD also only shows 111 GB. This is with a fresh install of Windows 7:

enter image description here

As Ben points out this caused by a combination of reserved space for wear leveling and the marketing material using base 10 when your computer uses base 2.

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