3 Replies Latest reply on Feb 20, 2015 12:42 PM by jonathan_intel

# Need help understanding program\erase cycles vs total bytes written (SSD 525 64GB)

I read that the 525 SSD is rate at 5000 p/e.

Is the total bytes available before failure equal to the size of the SSD x P\E? therefore, 64GB x 5000P/E = 320000 GB (312.5 TB)?

This contradicts the specs which claims that the "Minimum Useful Life/Endurance Rating" is 20 GB/Day for 5 years. So, 20GB x 365 x 5 = 36500 GB (36.5 TB)

312TB compared to 36.5 Tb is quite different. Can someone clarify the best method/calculation to understand how much data can be written to the card before failing? and how can the p/e be used to calculate the total bytes that can be written?

Thanks

• ###### 1. Re: Need help understanding program\erase cycles vs total bytes written (SSD 525 64GB)

Hello Paul Moufrage,

Here is some information that will help you understand the endurance information.

The actual Useful life of Intel® Solid-State drives involves a complex set of factors, for this reason, there is no simple formula for calculating the specific endurance a given SSD will experience.

Some of these factors include (but are not limited to):

-    Workload (sequential vs. random writes)

-    Compressibility of data

-    Write Amplification Factor (this is mostly a consequence of the workload)

The figure of 20GB of host writes per day for 5 years is calculated using Global standards for Reliability specifications, and should be viewed as the minimum amount of data you would expect to be able to write before the Media Wearout Indicator is reduced to 1. However, most Intel® SSD 525 Series 60 GB should be able to exceed those values.

• ###### 2. Re: Need help understanding program\erase cycles vs total bytes written (SSD 525 64GB)

Hi Jonathan,

Thank you for the reply. I was hoping to get a little more direction but understand what you're saying.

Perhaps my user case can shed more light. The targeted work load is 200GB of written data per day on the ssd. Think of it as temporary data caching. With a  "Minimum Useful Life/Endurance Rating" of 35TB, the ssd will only last about 6 months. I understand the minimum rating is typically very conservative, and I've seen reports where the SSD outlives the rating by leaps and bounds. I was just wondering if there was any other way to get a ballpark figure of how long it will last.

How about if I put the SSD under the desired workload and let it run for a month, will I be able to extrapolate the estimated life by monitoring the SSD SMART wear property? is wear linear?

thanks

• ###### 3. Re: Need help understanding program\erase cycles vs total bytes written (SSD 525 64GB)

Hello Paul,

You should be able to get an approximate with the method you mentioned. The best indicator for the expected useful life of the SSD is the SMART attribute E9h: Media Wearout Indicator, this attribute declines linearly from 100 to 1 as the average erase cycle count increases from 0 to the maximum rated cycles.

Once the normalized value reaches 1, the number will not decrease, although it is likely that significant additional wear can be put on the device.