7 Replies Latest reply on Nov 21, 2009 10:49 PM by tingshen

# How to measure GB/day?

The datasheet for Intel's X25-M SSD states that it should last at least 5 years when written to 20 GB/day. Can anybody recommend a Windows software that can actually measure how much raw data gets written to the disk? I'm not really that worried about the endurance of my SSD, but I'm hopelessly curious.

• ###### 1. Re: How to measure GB/day?

In intel SSD toolbox, check smart atributes, theres a atribute called host writes, here it reads 629 GB and my drive has +- 30 days.

629/30 = 20,9 GB.... lol on the spot, i guess it will be a bit less than 5 years for me lol

Now I need a better excuse to buy a new one in the next 2 years.

• ###### 2. Re: How to measure GB/day?

Question is if the 5 years at  20GB/day spec. is for the 80 GB or for the 160GB drive ?

The bigger driver has twice the space, so it should last twice the time for a 20GB/day usage ?!

• ###### 3. Re: How to measure GB/day?

Thanks for the SMART tip! It basically answers my question.

Intel's SSD Toolbox shows Host Writes (ID: E1) in gigabytes so it's easy to understand. But CrystalDiskInfo, for example, shows only the raw value in hexadecimals. Here's how to decode a raw value to gigabytes:

• Make sure you have the raw value in decimals and not in hexadecimals. CrystalDiskInfo shows 1471 for my SSD and this is in hexadecimal. It's 5233 in decimals. HD Tune, for example, shows the value in decimals already.
• Divide the raw decimal value by 29.8 (this is 1 / (512 * 65536 / 1000000000))
• The result is total writes in GB where one GB = 1000000000 bytes.

So for example my rather new SSD has been written to 5233 / 29.8 = 175.6 GB.

When Intel says that the minimum useful life is 5 years with 20 GB/day writes, they mean that nearly all individual drives out there should endure that. I don't know what are the strict parameters they are using, but the point is that it should be very uncommon for a drive not to endure this.

Now consider this in contrast: When people talk that a NAND flash cell lasts 10.000 erase/write cycles (I don't know how well this holds true for Intel SSDs) what it actually means is that if you drew a bell curve, the curve would peak at 10.000. In other words: after 10.000 erase/write cycles, on average, half of the cells are dead and half are still working. So it's not anymore usable as an SSD, and hasn't been usable for a long time.

The lifespan estimates are basically just based on probabilities. This 5 years @ 20 GB/day has a very high probability of being true, so on average, your drive should last much longer.

That's why it's so difficult to draw any definite conclusions from these figures when all they give you are probabilities. Basically it all boils down to this: Are you feeling lucky?

(Edited: Added instructions to convert Host Writes to gigabytes)

• ###### 4. Re: How to measure GB/day?

Micron admited that their 34nm MLC NAND ony support 5000 cycles, not 10 000 as usual.

(Samsung seems to have even much more trouble with their 32nm MLC NAND, that explain why their not available now for SSD usage).

But Micron/Intel is working on MLC Nand thats supports 30K cycle, that's a good news:

http://www.micronblogs.com/2009/10/huge-reliability-from-tiny-nand/

• ###### 5. Re: How to measure GB/day?

Seems like the toolbox is no longer available to prevent further damage....

the choice of paying a little more for G1 SSD does pay off now.....

but I can't measure my SSD lifespan now....does it work when it's connected via Adaptec storage controller?

• ###### 6. Re: How to measure GB/day?

I checked my smart in the toolbox:

Power on hours 2671

Power cycle count 295

Unsafe shutdown count 281 ????? ( must be wrong i always shut compu down normally, might have to do with fact i disconnect power every night)

Host writes 3.81 Tb

so my hourly host writes are 3.810/2671 = 1.426 Gb / hour on 10 hour day this is 14.26 Gb so i should be ok.

I do however have the famous freeze problem again, but this is a diff story.