Hard Drives Vs. SSDS

[Watashi]

What is the average lifespan of a HDD compared to a SSD? I figured that SSD would be better because it doesn't have mechanical parts.

[DrM]

ssds are more reliable unless you do lots of writes to disk because they dont have moving parts

[Ryoutarou97]

1 minute ago, Doomerson said:

What is the average lifespan of a HDD compared to a SSD? I figured that SSD would be better because it doesn't have mechanical parts.

SSDs actually have a limited number of writes they can take, but it goes well into petabytes for even small ones (this was tested by tech report writing to them 24/7 for well over a year, maybe two, after which they could still read from them) so unless you're using it for something really intense you're fine. I've seen HDDs that are well over a decade old and still working, so unless you're looking to use them in some insanely edge case the answer to both is long enough.

[AresKrieger]

Depends on the parts chosen but an SSD should last longer if you don't constantly write large amounts of data to it where as HDD will die eventually if it is used at all, so it's a matter of circumstance if this was a few years ago I'd say HDD last longer (old SSDs were crap) but now SSDs would get my vote so long as they are powered ocasionally (they will lose data eventually if say left on a shelf if it is certain types of SSDs)

[ARikozuM]

I've seen HDD's last as long as SSD's and SSD's last as long as HDD's. It just depends on the precautions the user takes for them.

[Drak3]

A good quality HDD will outlive an SSD if both see the same usage. That said, even a crappy SSD from any reputable brand should last 5-7 years under normal usage, and speed increase of an SSD is something to consider.

[Streetguru]

40 minutes ago, Doomerson said:

What is the average lifespan of a HDD compared to a SSD? I figured that SSD would be better because it doesn't have mechanical parts.

Once an SSD runs out of write cycles is dead forever

 

I've got some working IDE hard drive lying around here

[luigi90210]

21 minutes ago, Streetguru said:

Once an SSD runs out of write cycles is dead forever

 

I've got some working IDE hard drive lying around here

its not dead dead, you can still read from it, you just cant write 

[faziten]

Here: 

 

Comprehensive lifespan of HDD distributed analysis

 

For SSD's the analysis is not there yet. You have first to bring reliable data from many years of validated use. Also there are already more than 5 SSD technologies, and in every case, the lifespan is dependent on the writes you do in the unit. The lower capacity units being the most affected since the recurrence may occur frequently. All in all you need to apply your personal workload into account to have a more accurate measurement. 

 

But for your future reference: 

 

SSD's tested agains TWO PETABYTES of Writing.

 

If you buy the proper brand and model and don't abuse with nonsensical uses it may last long enough four you to throw it away.

 

Hope it's useful! 

Cheers!

[mariushm]

A lot of hard drives fail in the first 3-6 months of 24/7 operation. Statistically, if a hard drive survives this period, it's going to last for at least 5-7 years. After this period - again statistically - the failure percentages go up with every year. It's not uncommon though to have 10 years old hard drives still working.

A hard drive that's turned off and on lots of times, statistically it's going to fail faster than a drive which runs 24/7. Hard drives (platters, the printed circuit board) don't like fluctuations in temperature, it's better for hard drives to reach a specific temperature and stay there for their whole operating time.

 

In general (but you can't rely on it), when a hard drive fails, you're going to know in advance by the sound it makes or by increased number of warnings in the SMART information. This often can give you from at least a few hours in the worst case scenario to days of operation at reduced performance to backup the data.

 

SSDs often fail in uglier ways.. the controller firmware gets corrupted so it can not longer recognize the structure of the data in the flash memory chips, or it just gets stuck in a loop and you don't even see the SSD in your system anymore,,, much rarer, the flash memory chips themselves get damaged and won't even talk to the ssd controller anymore (in which case you may still recover data if you take the SSD drives to a specialized service)

Anyway the point is that most often, with SSD drives if they fail, they fail hard and you lose data.

 

SSDs have a limited number of erase cycles, not writes. Data is organized in "pages" of 512 KB of information and each page has several units of 4KB of data... the SSD controller can write any amount of 4 KB chunks but in order to overwrite such a 4 KB chunk with something else, it needs to erase the whole 512 KB page where the 4KB chunk is part of (and basically when this happens the SSD controller just reads the other 4 KB chunks and spreads  them around in other pages that aren't fully used, and marks the page as ready for erase but doesn't actually erase it unless it really has to, because it takes several times more time to erase a page then just write chunks of data, and would decrease performance of the SSD drive). When idle, or when user forces a TRIM command, or when it hasno other choice, the SSD drive may parse the memory pages and "liberate" some pages marked as good to erase and make them ready to accept new 4K writes.

 

So like i said, SSDs tend to not erase pages, unless they have no other choice, so they juggle with 4 KB blocks and constantly move and spread them around to reduce the number of erases and increase the lifetime of a drive.

Another interesting consequence of this is that the data is not physically arranged exactly as the operating sees it. With regular hard drives, you may know that file a.txt is stored at sector 100 on the drive, so you could software to scan the read the first  100 sectors and you'll find the contents of file a.txt in sector 100.

With SSD drives, if the operating system tries to create a file and put contents in sector 100, it doesn't mean that the actual bits will be in the first memory chip, at positon 100 times 4KB. The SSD controller inside a SSD drive spreads the 4K writes around in all memory chips and keeps track of where everything ends up, so it knows what to read back when needed. That's one of the reasons why defragmenting a SSD drive is worthless - you'd be happy to see continuous files in your defragmenting application but secretly the SSD drive still has the files spread all over the memory chips inside anyway... by defragmenting you just make the SSD drive write to memory chips pointlessly. 

 

SLC flash can do 10k+ erases , MLC can do up to maybe 5-7000 erase cycles but the more you miniaturize transistors, the lower the number - older 30-40 nm could handle maybe 5000 erases, but modern 20nm MLC may only handle 2000-3000 erases.  TLC can do maybe 1000-3000 depending on manufacturing techniques, how low the size is and so on.

When a particular "page" of flash memory hits the maximum erase cycles count, it becomes read only and the ssd controller moves the contents to other pages and "blacklists" that page, it stops using it, and replaces it with a page from the extra memory hidden from user (up to a point, when it's too much the SSD will just say it's done and refuse to write, will trigger SMART warnings and stuff like that) ...

SSD controllers extend the life of SSD drives by hiding from user a few GB worth of memory and automatically replacing "spent" memory pages with fresh memory pages from the area that was hidden from user . That's why you see weird SSD sizes like 200 GB or 220 GB, when all flash memory is in multiples of 8 (so a 200 GB drive actually has 240 or 256 GB of flash memory, depends on how many flash memory chips it uses internally).. the hidden portion is used as reserve and to cache files in some cases.

 

SSD Manufacturers use warranties that usually correlate with the amount of information a user can normally write on a SSD before they predict a lot of pages will hit their erase cycle limit. 

 

For example, you'll see a manufacturer say the 250 GB SSD can do 70 GB of writes a day and is warrantied for 5 years .. that just means they estimate that in total they guarantee you'll be able to write 70 GB x 365 days x 5 years = ~ 128 TB of data on the SSD or about 500 times the whole 250 GB of SSD being overwritten. They bank on the SSD controller being smart enough to juggle the chunks of data around to extend the life and limit the erase cycles enough to make this possible .. at the end of so much information being written in the memory chips, some pages may have been erased as little as 300 times, others could be up to 800-900 but the huge majority under the rating of 1000 erase cycles.

 

If you write less data than what they estimate, the SSD may last longer .. if you write more than the values they give every day, the SSD may reach its end of life sooner than the warranty period (and they will refuse to replace your drive if you exceeded that write quantity,, the amount of data written to it is stored in SMART values)