Question about my SSD

[Nekoboy@1441834147]

Hi guys,

I just recently got myself a 120g SSD that I'm going to use for my OS and a few other things. My question is, when I was installing windows 7 on it i noticed that when I was selecting which hard drive to install windows into, it showed my SSD as only 112gb not the 120gb it was suppose to be.


Why am I not getting the whole 120gb of space?

 

[lonewolf7]

The rest of the space is taken by hardware and MBR. Its normal.

 

[noise]

I'm afraid the above is not accurate (but is a common misconception).

Drive manufacturers list drive sizes using different units. i.e. by their standards one GB is 1000000000 bytes. To rest of the world one GB is 1073741824 bytes.

So you can see that this discrepancy causes many people to wonder where their space has gone. As a rule of thumb, expect to only get about 91% of the listed capacity.

 

[Nekoboy@1441834147]

Then they lied to me.

 

[noise]

Not in a way that would stand up in a court of law. But yes I agree it is not very helpful. Unfortunately for the consumer they do print this information in enough places to get away with it. Just so you are aware this has been the case with drives for a long, long time. it is not something new to SSDs but the premium price and smaller capacities makes you notice it more.

It is like the long and short scale. A billion can be a million million (long scale) or a thousand million (short scale).

 

[JohnnyLucky]

10% less capacity than what manufacturers advertise is just about right.

The first problem is the way ssd manufacturers advertise storage capacity. They round off the numbers as noise already mentioned. Hard disk drive manufacturers do the same thing. In the advertising business it is known as "cream puffing". The practice can be quite creative.

The vast majority of your missing capacity consists of space set aside for overprovisioning. Typically about 7.5% of an ssd's total capacity is set aside for that purpose. Samsung recommends 10% for their ssd's. The space reserved for overprovisioning will not be available to you.

 

[Nekoboy@1441834147]

What is overprovisioning?

 

[JohnnyLucky]

SSD Over-Provisioning is a technique used in the design of SSDs. By setting aside some of the capacity, which the user cannot access, the SSD controller can more easily create pre-erased data blocks that are ready to be used in a virtual pool.

The two main benefits of Over-Provisioning are faster overall write IOPS and better reliability. In terms of reliability, the reserved capacity is also used to replace bad memory blocks.