Who cares about dwpd?

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ColPanic

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Feb 14, 2016
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Given that the vast majority of datacenter drives see actual usage that is far less than the manufactures rating. Used enterprise SSDs: Dissecting our production SSD population Is dwpd becoming a useless metric? Unless you are buying a drive for an application that you know will actually be write really write intensive (in which case you should be looking at lower latency pcie options anyway), endurance ratings may become one of those unimportant specs in computer tech? Not quite as meaningless as the contrast ratio of a monitor, but far less important than other things like performance specs.

I'd be willing to wager that 99% of these sata drives are going into places where 10-15k spindles were a few years ago. So, assuming a 5 year replacement cycle, why is write endurance even marginally important?
 

Patrick

Administrator
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Dec 21, 2010
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If I can provide points from a slightly different perspective:
  • If you are buying used, there is a better chance lower endurance drives will have less total endurance than higher endurance drives by the time you get it.
  • If you are buying new, one of the biggest reasons for using across the board higher endurance SSDs is that you do not have to think about endurance across all of your servers/ SSDs. No need to put write heavy VMs on high write endurance SSDs.
 

T_Minus

Build. Break. Fix. Repeat
Feb 15, 2015
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From what I've seen write endurance SSDs are commonly also higher performing during the actual write too, so you get both even if you only needed faster sustained writes.
 

nk215

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Oct 6, 2015
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for my use anything more than 1tb write/day for 5years is over kill. So eMLC is about as great for me as SLC.

That's why I didnt jump onto the $190 (shipped) deal for samsung PM drives.


Sent from my iPhone using Tapatalk Pro
 

J--

Active Member
Aug 13, 2016
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Because a 5 year old SSD is worth a tiny percentage of what it cost new.
Huh? You've been soapboxing about this in multiple threads on this forum, I'm not sure what you're trying to achieve.

The silicon has a limited write endurance, dwpd was created to give end users an feel for what workload it's appropriate for. If you're far away from the drive's rated write endurance, your drive could ostensibly last 2x or 10x its warrantied lifespan (assuming all other supporting functions still work).

Not sure why the value of the drive 5 years down the road really matters, nobody is investing in computer hardware for its residual value. If my drive has only 10% "used" of its rated write endurance, why should it be tossed? Spinning rust had the disadvantage that they would self-destruct after a certain number life span, but there is no mechanical failures of SSDs short of running them over.

If you're running a datacenter trying to optimize rack density, then you might consider cycling them out, but only until there's a huge advance in platform performance/watt will there be wholesale changes.
 

ColPanic

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Feb 14, 2016
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Soapboxing? I started one thread and answered one other. My point regarding 5 year replacement and residual value is that most users aren't going to hold on to an ssd longer than 5 years. They will be able to buy other drives with much better performance and much larger capacity for less than they paid for the old one. I don't know many people still using X-25m's but they'd probably still work. So a drive that may last 25 years is not necessarily any better investment than one that may only last 10.

The same is true for ram and cpus. Nobody worries about when they will wear out because it will most likely be replaced far sooner.
 

aero

Active Member
Apr 27, 2016
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5 years isn't that long. I'd be very upset if my drives only lasted 5 years. A high DWPD rating is very important when buying used SSD, as you have a much better chance of getting a drive with lots of usable life left.
 

fractal

Active Member
Jun 7, 2016
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You say potatoe, I say potatoe... I guess it sounds better when you say it out loud.

I don't really care about DWPD. I do care about DWPD * DAYS * CAPACITY. I, like many home users, run my drives long past the 2 / 3 / 5 yr rating. So, if if my 100G drive has 5 DWPD times 1 YR rated, it will probably last me fine for 5 or 10 yrs at my much lower usage.

But for someone why buys equipment with the expectation of replacing it after 3 yrs? For them the DWPD rating is criticial to ensure the drive has not failed when they scrap it. Then again, replacing a failed drive often costs many times the price of the drive and is much more expensive than replacing a perfectly good drive after the end of its service life during planned maintenance.