SSD Endurance Diary with OCZ Vector 256 GB
Category : Storage
Published by Marc Büchel on 06.08.14
Meanwhile most enthusiasts have an SSD in their PC and since manufacturers are successfully conquering the mass maket with SSDs, these new, quick drives are nowadays widely spread. In the past there were quite a few drives that died an all sudden death. Even today customers are not sure for how long their SSD will last and especially the P/E-cylce count (program/erase cycles) is something that worries quite a few well informed users. In this diary we're going to check what it takes to use up all P/E-cycles an OCZ Vector SSD has to offer, that features 256 Gigabyte capacity. So what is your guess, how long is it going to take until the drive refuses to work.
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Reliability of SSDs appears to be a topic on which useres would like to get additional information. In order to get a feeling for how long SSDs are actually going to survive heavy torture testing, we're trying to write on an OCZ Vector SSD with 256 Gigabyte capacity until the NAND flash memory starts to go over into the read-only mode. Read-only mode is acutally a good keyword. Most users associate dying NAND flash memory with a dying SSD. These are actually two different things. If you're worried about using up all P/E-cycles of the NAND on the SSD you bought, this doesn't mean, that, even if you manage to do so, your SSD isn't responding anymore. When a NAND flash cell is out of P/E-cycles then it goes into a read only state, meaning you'll still be able to retrieve data in order to make a backup. Users usually associate using up all P/E-cycles with the absolute worst case, which would be a drive that doesn't respond to anything anymore.
| Page - 1 - Introduction | Page - 5 - Day 7 |
| Page - 2 - Test procedure and test environment | Page - 6 - Day 22 |
| Page - 3 - Day 1 | Page - 7 - Day 39 |
| Page - 4 - Day 2 | Page - 8 - Day 142 |
Test procedure and test environment
In this test we want to get to the point where we've used up as many P/E-cycles as possible to then show what can still be done with such an SSD. In an effort to do so, we're using Iometer where we've setup workers that do constant, sequential writes, which is basically the one way to get rid of as many P/E-cycles in as little time as possible. As you can see from the screenshot below, the test drive we're running these tests on has already been used and a total of 500 Gigabyte has been written on the NAND before we started with the acutal endurance test. In the lower part of the screenshot you find all relevant smart data and should you be a little bit familiar with S.M.A.R.T. data, then you'll notice this is a perfectly healthy drive.
Diary
We're going to update this article on a daily basis. Each day we will add a new page to this article where we post a screenshot of CrystalDiskInfo. If there is anything suspicious going on with the drive we will point it out and explain why this is happening.Test Setup
| Mainboard | ASUS P9X79-E WS |
| CPU | Intel Core i7-3930K |
| Memory | G.Skill Ares 2133MHz 16GB |
| Video | ASUS GTX 650 |
| Software | Windows 7 x64 |
| PSU | Seasonic X-Series 1250 Watt |
| SSD |
OCZ Vector 256 GB Endurance: 20GB host write for 5 years ~ 36.5 TBW |
| Page - 1 - Introduction | Page - 5 - Day 7 |
| Page - 2 - Test procedure and test environment | Page - 6 - Day 22 |
| Page - 3 - Day 1 | Page - 7 - Day 39 |
| Page - 4 - Day 2 | Page - 8 - Day 142 |
Day 1
Today there was nothing suspicious going on. The drive was working the way it is expected to be working. So far we've managed to write 5500 Gigabyte. If we check "Total Host Writes" and compare them to "Total NAND Writes" we can make a different assumption. I looks like this makes the actual "Write Amplification Factor" of the drive visible. Since the host writes stand for the actual amount of usable data that has been written, the "Total NAND Writes" show how much data acutally had to be written in order to store that amount of data. Let's dived "Total NAND Writes" by "Total Host Writes" and we might have a good approximation of the actual write amplification factor of this drive. In this case there appears to be a WAF of 1.46. Since this value is somewhere in the between 1 and 2 it is really good.
| Page - 1 - Introduction | Page - 5 - Day 7 |
| Page - 2 - Test procedure and test environment | Page - 6 - Day 22 |
| Page - 3 - Day 1 | Page - 7 - Day 39 |
| Page - 4 - Day 2 | Page - 8 - Day 142 |
Day 2
On the second day there is no noticeable difference apart from the fact, that the "Remaining Life" value, that comes from the S.M.A.R.T. data, went down by two percent to 96 percent. Assuming the drive keeps degrading at this rate, then we will hit 0 percent in about 48 days. Keeping in mind we're averaging about 10 Terabytes written per day we will have to write roughly 500 Terabytes to reach the point where the NAND flash is out of P/E-cylces.
| Page - 1 - Introduction | Page - 5 - Day 7 |
| Page - 2 - Test procedure and test environment | Page - 6 - Day 22 |
| Page - 3 - Day 1 | Page - 7 - Day 39 |
| Page - 4 - Day 2 | Page - 8 - Day 142 |
Day 7
It is been seven days now we're trying to run out of NAND flash cycles and still the drive is reporting 90 percent regarding health status. If things keep on going like this, then we will have to write ten times as much data then what we've done so far. The screenshot above is showing you, we've been writing 45 Terabyte to the OCZ Vector with 256 Gigabyte capacity. If we now keep in mind, that OCZ is specifying endurance for this drive with 20 Gigabyte written per day, translated into total Terabytes written it means 35 Terabyte. In other words we've surpassed that value by 10 Terabyte already and remaining life is still at 90 percent. It is starting to look like, OCZ in this case, was engineering this drive with a rather large factor in mind regarding endurance. So far it appears this drive is going to survive at least ten times the total NAND writes, which OCZ advertises in the specs.
| Page - 1 - Introduction | Page - 5 - Day 7 |
| Page - 2 - Test procedure and test environment | Page - 6 - Day 22 |
| Page - 3 - Day 1 | Page - 7 - Day 39 |
| Page - 4 - Day 2 | Page - 8 - Day 142 |
Day 22
As you can see from the picture above, we've meanwhile managed to write a little bit over 200 Terabyte on the OCZ Vector 256 Gigabyte. This is in fact about six times as much as OCZ advertises this drive for. A quick look at the "Remaining Life" value in the S.M.A.R.T. data reveals there is still 54 percent of life left, meaning we might have to write even more than 400 Terabyte until some magic starts to happen. So far it also doesn't matter what we do with the drive it simply does what it's supposed to do in the way you expect things to be done. Also performance is still on a resonable level. In order to show you that peformance is not degrading, we attached an Atto screenshot, which indicates that you still get rather reasonable performance from this drive.
| Page - 1 - Introduction | Page - 5 - Day 7 |
| Page - 2 - Test procedure and test environment | Page - 6 - Day 22 |
| Page - 3 - Day 1 | Page - 7 - Day 39 |
| Page - 4 - Day 2 | Page - 8 - Day 142 |
Day 39
In the meantime we've been writing more than 400 Terabyte on the OCZ Vector 256 Gigabyte Drive. After this toruture the "Remaining Life" Value is still at 3 percent and the drive runs perfectly flawless. This means it starts up without any issues at all and also performance is still what it should be like. Overall we're curious to see what's going to happen, when "Remaining Life" drops to 0 percent.
| Page - 1 - Introduction | Page - 5 - Day 7 |
| Page - 2 - Test procedure and test environment | Page - 6 - Day 22 |
| Page - 3 - Day 1 | Page - 7 - Day 39 |
| Page - 4 - Day 2 | Page - 8 - Day 142 |
Day 142
This has been our first endurance test of an SSD. At the beginning of this diary we've been trying estimate how long it will take until the drive is going to die. It turns out that calculating with 5'000 P/E-cycles was a reasonable thing to, since in the end the drive achieved 5'129 P/E-cycles. We were guessing the drive would withstand our torture testing of continuous writing for 125 days and that turned out to be close to the actual value too, whereas the final result was 142 days.
If we start to do the maths, based on the values we gathered we're going to see some rather surprising endurance values. OCZ specifies this drive to be capable of enduring 20 Gigabyte written per day over a time period of five years. This is what the manufacturer of this drive guarantees. As you can see from the table below, based on our results, when writing 20 Gigabyte per day, you could use this drive for 121 years. This is over 24 times more than actually advertised and it gives you a feeling on how conservative manufacturers are when it comes to endurance ratings of their SSDs. Even if you were writing 50 Gigabyte per day the drive would still last 48 years and at 100 Gigabyte per day this Vector 256 GB would run for 24 years.
Lately another endurance rating used by manufacturers started to appear. Now the vendors are talking about drive writes per day. Some enterprise grade SSDs for example are capable of delivering ten drive writes per day over five years. Pair this up with a drive capacity of 1 Terabyte and you will get some seriously high numbers. Calculating drive writes per day (DPWD) for the Vector 256 GB we've been testing here, when factoring in a period of five years, we end up with a value of 1.89. In the end this means you could be writing the capacity of the drive over 1.8 times per day for five years.
Since the Vector 256 GB is a consumer drive and consumers will be the ones buying and using such a drive, a suitable use case should be applied. In case of an average user it's highly likely that no more than 20 Gigabyte will be written on the drive per day, which is over 24 times less then what the Vector 256 GB could actually do.
| Data written per day | Host Writes | NAND Writes | WAF | Cycles | Endurance |
| 10 GB | 884 TB | 1'313 TB | 1.48 | 5'129 | 242 years |
| 20 GB | 884 TB | 1'313 TB | 1.48 | 5'129 | 121 years |
| 50 GB | 884 TB | 1'313 TB | 1.48 | 5'129 | 48 years |
| 100 GB | 884 TB | 1'313 TB | 1.48 | 5'129 | 24 years |
| Page - 1 - Introduction | Page - 5 - Day 7 |
| Page - 2 - Test procedure and test environment | Page - 6 - Day 22 |
| Page - 3 - Day 1 | Page - 7 - Day 39 |
| Page - 4 - Day 2 | Page - 8 - Day 142 |