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Community Manager

ssd 520 240gb overprovisioning

Hi every one, i ave just bought 2 intel ssd 520 240gb. i want to configure them in Raid mode (mirroring). I want to use the overprovisioning on the drives, what should i do? is enough to format both drive in one partion of 180gb and left the remaining space unformatted?

do i have to do something else to enable overprovisioning?

thanks a lot.


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I don't think you need to over provision, providing you only use 180 Gig on each drive the spare space is used anyway for wear levelling regardless if it is formatted as available or not. The free space is also prepared using Trim to be write ready for faster writes. The reason you might not want to partition the whole drive is to guarantee you have over provisioning as you can never fill up the entire space. Also a certain amount is already allocated to this task and unavailable to us anyway.

So the answer is yes just partition the drive but leaving some space, that is all you need to do, but it isn't necessary to have free space un-partitioned in order for the drive to use it, just formatting the whole thing will always see spare space used for drive management, providing you don't completely fill it up with data.



Community Manager

thank you Phil!

reading this article its seems that the reviwer tests the drive with and without overprovisioning, so i thought that there was a method to enable or disable it.

after you reply i can't understand how they tested it without overprovisioning (as you said it is an automatic feature of the drive).

any way i'd go leaving 20% of the space unformatted in both the drives.

thanks again.


Community Manager

Guiseppe, In that review, all they did to "over provision" the SSDs is the same thing you will be doing, just create the user partition size less than the full size available.

Phil is saying that the 520 SSD already has space beyond its normal 240GB size that the user cannot access. The 240GB 520 SSD actually has 256GB of capacity, but 16GB is set aside as over provisioning space.

This is how they described their over provisioning method in that review:

With the Intel SSD 520, we benchmarked performance in steady-state with stock overprovisioning as well as 20% over-provisioning. At the 20% OP state, the 240GB Intel SSD 520 turns into a 192GB SSD.


When they said "stock over provisioning", they mean what Phil was talking about, and I described in detail.

When they said "20% OP state", they mean setting the partition size in the SSD from 240GB to 192GB, to create the extra 20% over provisioning. I'll call that manual over provisioning, since you must do it yourself.

I imagine you are asking about this, because the test results in that review show that the SSDs that were manually over provisioned, performed better than the ones that were not, and left at their normal size, right?

That result seems to tell us that just leaving free space unused as Phil said (which is what we have been told in the past by some experts) does not seem to be completely true. That is a surprise to me too, which I don't quite understand right now, but I'll try to understand what is happening there by doing some more reading.

Anyway, it seems you are doing things right by manually over provisioning, which I did too with my RAID arrays of 520's. Thanks for posting about this, it has me wondering what is going on. I have the feeling I'm missing another detail that the review may not be mentioning. If not, this is an important thing to know.

Community Manager

thanks parsec now everything is clear

i just received my two intel 520 ssd and i did some tests, but i got some weird result.

i tested them in my desktop with a sata3 bus. i already have an 80gb Intel X25-M SSD so i did some comparison:

on sequential reading with Crystal disk mark i got 220Mb/sec on my old X25 while i got only 120Mb/sec with the new intel 520... it seems pretty strange to me that my old disk performs better than the new one

on sequential writing things are different, i got 50Mb/sec on the X25 and 110 Mb/sec on the new intel 520

these data are so different from the ones i read on this review Intel SSD 520 Enterprise Review | - Storage Reviews

i know that they tested the drive with a sata 6 bus, but the result i got seems very strange to me. how my old x25 can perform faster then the new intel 520?

any suggestion?

thank you very much


Community Manager

Giuseppe, Something is not right, but there are several things to check before deciding the SSD is bad.

First we need to know the parts in your PC, or the model if you bought it already built. If you built it, what mother board, CPU, and operating system do you have? After that, you need to check which SATA ports on your mother board you are using for your SSDs, particularly the 520 and your X25. We also need to know what SATA mode your BIOS is set to, and what SATA driver you are using.