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HET MLC: What Does Endurance Really Look Like?

Intel SSD 710 Tested: MLC NAND Flash Hits The Enterprise
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Intel won't tell us exactly how many P/E cycles its 25 nm HET MLC can withstand. However, we don't have to rely solely on the company's word with regards to the 710's high endurance spec, because we can backwards-calculate the number using S.M.A.R.T. values found on Intel's latest SSDs.

Intel S.M.A.R.T.
Workload Counters
Purpose
E2
Percentage of Media Wear-out Indicator (MWI) used
E3
Percentage of workload that is read operations
E4Time counter in minutes


The media wear-out indicator is a S.M.A.R.T. value (E9) on all SSDs that tells you how many P/E cycles are used, on a scale from 100 to 1. This is like the odometer on a car. However, using this value would require months of testing, because its on a scale from 100 to 1. 

In comparison, Intel's workload counters are kind of like trip counters on a car, because they measure endurance over a fixed time period. Better yet, they provide more granular information on wear-out out, which makes it easy to measure endurance in a under a day. However, none of these workload counters are generated until the drive has been used 60 minutes or more. In practice, one hour isn't long enough for us to take a precise measurement, which is why we our endurance values are based on a 6 hour workload.

The counter starts the minute you plug in the drive, so you'll need to reset it if you want to attempt this test on your own. This is possible by sending a 0x40 instruction via smartctl.

If you're using a disk information program like CrystalDiskInfo, all S.M.A.R.T. values are in hexadecimal, which means you'll need to convert to decimal before proceeding. The E2 field is particularly unique because it's only valid out to three decimal places, and it's stored in an IEC binary format. So, after converting the E2's raw value to decimal, you have to divide by 1024 to get percentage.

Before we get to the results of our tests, we need to cover a little bit of math. If we toss out the JEDEC formula for a second, what do we know about write endurance? Rules that apply to all SSDs:

  • Host Writes ÷ NAND Writes = P/E Cycles Consumed ÷ Total P/E Cycles
  • P/E Cycles Used ÷ P/E Cycles Total = Media Wear Indicator (scale of 100 to 1)
  • 100% sequential write means Host Writes = NAND Writes (write amplification = 1)


If we take these three formulas, it's possible to calculate the write endurance of the SSD 710 using the SSD 320 as a reference point.

128 KB 100% Sequential Write
6 Hours
Intel SSD 710
200 GB
Intel SSD 320
300 GB
Total Data Written
3.88 TB
3.9 TB
Percent MWI used (E2)
0.053
0.238
Endurance In Years
1.292
0.287
Percent MWI per TB
1.35 x 10-2
6.10 x 10-2
P/E Cycles Per TB
3.07
13.7
P/E Cycles
22 337
5000
Recalculated Endurance Rating
(P/E Cycles ÷ P/E Cycles Per TB)
7268 Terabytes Written364 Terabytes Written


Starting with a 100% sequential write (write amplification equals one), we see the SSD 710's write endurance is roughly 4x to 5x higher than the SSD 320. We'll keep things simple and average out to 4.5x.

Previously, we've heard Intel mention that the NAND in its SSD 320 is rated for 5000 cycles. So, that puts the SSD 710 somewhere between 20 000 to 25 000 P/E cycles, which is in-line with what the company's competitors say eMLC should be able to do.

Now that we know what MWI looks like with a 100% sequential write, we can check write amplification in a random write workload with a high queue depth.

4 KB 100% Random Write
QD= 32, 6 Hours
Intel SSD 710
200 GB
Intel SSD 320
300 GB
Total Data Written
0.23 TB
0.11 TB
Percent MWI used (E2)
0.016
0.084
Endurance In Years
4.28
0.83
Percent MWI per TB
1.35 x 10^-2
6.10 x 10^-2
P/E Cycles Per TB
15.65
37.73
Recalculated Endurance Rating
(P/E Cycles ÷ P/E Cycles Per TB)
1437 Terabytes Written
132 Terabytes Written
Write Amplification
5.09
2.75


Interestingly, write amplification is higher on the SSD 710. However, in the same period, the 710 can write twice as much data as Intel's 320. That'd purportedly be counter to the reason for more over-provisioning, but it'll all fall into place shortly.

Perhaps more important, both drives have endurance values better than what Intel cites, which just goes to show that the JEDEC spec tends to underestimate real-world endurance. With the same random workload, all of the SSD 320's P/E cycles would be consumed in less than a year, whereas the SSD 710 could continue working for another three years or more.

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  • -3 Hide
    whysobluepandabear , October 31, 2011 4:46 AM
    TLDR; Although expensive, the drives offer greater amounts of data transfer, reliability and expected life - however, they cost a f'ing arm and a leg (even for a corporation).

    Expect these to be the standard when they've dropped to 1/3rd their current price.
  • 4 Hide
    RazorBurn , October 31, 2011 6:48 AM
    To some companies or institutions.. The data this devices hold far outweighs the prices of this storage devices..
  • -3 Hide
    nekromobo , October 31, 2011 8:14 AM
    I think the writer missed the whole point on this article.

    What happens when you RAID5 or RAID1 the SSD's??
    I don't think any enterprise would trust a single SSD without RAID.
  • -2 Hide
    DjEaZy , October 31, 2011 8:29 AM
    ... glad, that i have vertex 3...
  • 0 Hide
    halcyon , October 31, 2011 10:04 AM
    Nice. Now let's see how many comments complain about the price. :sarcastic: 
  • 0 Hide
    halcyon , October 31, 2011 10:13 AM
    __-_-_-__with the reliability those have they will never ever find their way into any server

    My Vertex 3 has been very reliable and I'm quite satisfied with the performance. However, I've heard reports that some, just like with anything else, haven't been so lucky.
  • -2 Hide
    toms my babys daddy , October 31, 2011 11:50 AM
    I thought ssd drives were unreliable because they can die at any moment and lose your data, and now I see that they're used for servers as well? are they doing daily backups of their data or have I been lied to? ;(
  • 1 Hide
    halcyon , October 31, 2011 11:57 AM
    toms my babys daddyI thought ssd drives were unreliable because they can die at any moment and lose your data, and now I see that they're used for servers as well? are they doing daily backups of their data or have I been lied to? ;(

    SSDs are generally accepted to be more reliable than HDDs...at least that's what I've been lead to believe.
  • 0 Hide
    Onus , October 31, 2011 12:33 PM
    halcyonSSDs are generally accepted to be more reliable than HDDs...at least that's what I've been lead to believe.

    Yes, but when they die, that's it; you're done. You can at least send a mechanical HDD to Ontrack (or a competing data recovery service) with a GOOD chance of getting most or all of your data back; when a SSD bricks, what can be done?
  • 2 Hide
    CaedenV , October 31, 2011 12:48 PM
    nekromoboI think the writer missed the whole point on this article.What happens when you RAID5 or RAID1 the SSD's??I don't think any enterprise would trust a single SSD without RAID.

    The assumption is that ALL servers will have raid. The point of this article is how often will you have to replace the drives in your raid? All of that down time, and manpower has a price. If the old Intel SSDs were about as reliable as a traditional HDD, then that means that these new ones will last ~30x what a traidional drive does, while providing that glorious 0ms seek time, and high IO output.
    Less replacement, less down time, less $/GB, and a similar performance is a big win in my book.
    toms my babys daddyI thought ssd drives were unreliable because they can die at any moment and lose your data, and now I see that they're used for servers as well? are they doing daily backups of their data or have I been lied to? ;(

    SSDs (at least on the enterprise level) are roughly equivalent to their mechanical brothers in failure rate. True, when the drive is done then the data is gone, but real data centers all use RAID, and backups for redundancy. Some go so far as to have all data being mirrored at 2 locations in real time, which is an extreme measure, but worth it when your data is so important.
    Besides, when a data center has to do a physical recovery of a HDD then they have already failed. The down time it takes to physically recover is unacceptable in many data centers. Though at least it is still an option.
  • 5 Hide
    CaedenV , October 31, 2011 12:52 PM
    Oh! I almost forgot; GREAT review Andrew! I learned a lot on this one.
  • 3 Hide
    Anonymous , October 31, 2011 2:09 PM
    Lied to about what? And who are THEY? ... Life expectancy of SSD vs. Standard Harddrive? Thats always unknown, every unit is an animal unto itself. SSD's don't suffer mechanical issues however putting them ahead in my mind. Backups are determined by how much time you can afford to loose business-wise, how much data you have and how long it takes to recover to a point you backup at last. maybe your data is too valuable to have lost. In that case Mirror and even copy to a DR site, maybe even live. Best thing would probably be to trust your IT guy because you kinda seem lost :) 
  • 0 Hide
    halcyon , October 31, 2011 2:10 PM
    jtt283Yes, but when they die, that's it; you're done. You can at least send a mechanical HDD to Ontrack (or a competing data recovery service) with a GOOD chance of getting most or all of your data back; when a SSD bricks, what can be done?

    Its funny you mention that. Ontrack purports that they are quite adept at recovering SSDs.
  • -1 Hide
    mt2e , October 31, 2011 2:15 PM
    profit margins must be huge for a product with a simple memory swap
  • 0 Hide
    phate , October 31, 2011 7:04 PM
    So what's the difference between this and the P400e?
  • -2 Hide
    ruddenberg , October 31, 2011 7:40 PM
    Andrew Ku! Get the facts correct please !!!!

    Intel® SSD 710 Series 300/200/100GB
    Random Read (8GB Span) = no info
    Random Read (100% Span) = 38500/38500/38500 IOPS
    Random Write (8GB Span) = no info
    Random Write (100% Span) = 2000/2700/2300 IOPS

    Intel® SSD 320 Series 600/300/160/120/80GB
    Random Read (8GB Span) = 39500/39500/39000/38000/38000 IOPS
    Random Read (100% Span) = 39500/39500/39000/38000/38000 IOPS
    Random Write (8GB Span) = 23000/23000/21000/14000/10000 IOPS
    Random Write (100% Span) = 150/400/600/400/300 IOPS

  • -3 Hide
    cmartin011 , October 31, 2011 7:51 PM
    This is the best intel could come up with? i know reliability is important and all, but make the performance worth the price. at those dollar $ a much quicker PCI express solution could be afforded with some sorta redundant feature build in.
  • 1 Hide
    acku , October 31, 2011 9:16 PM
    ruddenbergAndrew Ku! Get the facts correct please !!!!Intel® SSD 710 Series 300/200/100GBRandom Read (8GB Span) = no infoRandom Read (100% Span) = 38500/38500/38500 IOPSRandom Write (8GB Span) = no infoRandom Write (100% Span) = 2000/2700/2300 IOPSIntel® SSD 320 Series 600/300/160/120/80GBRandom Read (8GB Span) = 39500/39500/39000/38000/38000 IOPSRandom Read (100% Span) = 39500/39500/39000/38000/38000 IOPSRandom Write (8GB Span) = 23000/23000/21000/14000/10000 IOPSRandom Write (100% Span) = 150/400/600/400/300 IOPS

    Read page 8. we covered that already.
  • 1 Hide
    campb292 , November 1, 2011 1:53 AM
    I find all the comments about data recovery very bizarre. What data would someone supposedly keep on a SSD (or HDD for that matter) that meets a threshold to warrant expensive data recovery in the event of failure, but not so sensitive to warrant a backup?

    My important info has a fresh original image and 2 daily backups that automatically create 12 hours apart. It takes about 5 minutes each and costs 29.99 a year. Come on people.
  • 0 Hide
    beenthere , November 1, 2011 1:55 AM
    This looks like more "experimenting" to see what enterprise will tolerate than a technical breakthrough. So far neither consumer grade nor the Intel 710 enterprise SSD impress me for performance, reliability and compatibility. It's certainly a painfully slow development on SSDs. Using consumers to beta test these drives is pretty unscrupulous IMO.
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