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I heard that SSD are less durable than HDD. Is it true ?

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My first reaction to your question was: "My experience is exactly the opposite." Read on for exactly why, but first some background...

Both spinning and solid state drives have a limited life-span. There are some that are of the opinion that SSDs have as good or better a life-span than similar spinning hard drives given the same usage patterns.

Note however that not all SSDs are created equal. There are SLC drives such as the Intel X25-E, which tend to be much more expensive ($300 for a 32GB drive), but also are faster at writes and are more durable. The other architecture is called MLC, and is less expensive but may not be as good during writes as SLC and also may not last as long, largely because the memory cells have to be re-written in larger chunks. However, newer SSDs have better management firmware and last quite well.

But, back to your question... Everyone in my small company is running SSDs on their laptops. I've been running an Intel X25-M in mine for at least a year, maybe closer to two. I'd never go back to a spinning disc in my main laptop because of durability.

If you drop a laptop and the hard drive is spinning, you are almost certainly going to need to replace the hard drive. Earlier this year I dropped my laptop while it was running and after that it wouldn't even power on. I basically had to have everything but the CPU, RAM, and SSD replaced (motherboard, display, most of the parts of the case...). 3 or 4 years earlier I had a similar drop with a spinning drive. It survived for around a week after that, but quickly started generating errors.

So, in a laptop or other bump-prone environment like a carputer: SSDs are more durable hands down.

Another thing to consider though is how they fail. SSDs fail because they can no longer erase the cells. SSDs don't overwrite data, they tend to have a pool of unused blocks that they erase and make ready for use, and writes of existing blocks are sent to these new locations, rather than erasing existing data and writing it. Spinning hard drives tend to fail because the mechanical parts wear out and they start generating errors while writing and reading.

So one theory is that when the SSDs fail because of write cycle issues. you can still read the data off the drive, you just can't write anymore. Effectively making your SSD a read-only copy of your data when it failed.

My experience so far is fairly limited, less than a dozen drives over a couple of years for SSD versus over a thousand drives over 15 years for spinning. However, so far I do not feel that SSDs durability compared to spinning discs is insufficient, even for non-laptop use. Some of the very early SSDs were real crap, we had one vendor's 16GB SSD that died after a few weeks of use, and the replacement also died after a few weeks of use. However, current products, since the first generation Intel X25-M, I've been very happy with.

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In theory? In practice! Unless the controller fails, SSDs simply have cells that become read-only after wires are exhausted. By then they're already obsolete 5 generations or more at the current rate. –  Mircea Chirea Dec 13 '10 at 11:08
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@iconiK, the reason I say "in theory" is that that only accounts for the flash hardware side of it. I don't have any practical experience with how the file-systems will respond to having the drive suddenly go read-only, particularly with respect to being unable to flush data from their buffers into the flash, meaning the data on the flash may not be in the state of consistency that you would hope after a power-cycle. I don't expect my file-system to be able to mount or a copy to fsck cleanly after this sort of failure. It might happen, but I wouldn't be surprised if it choked... –  Sean Reifschneider Dec 13 '10 at 12:06
    
the whole flash drive won't get suddenly into read-only mode, just some cells, so filesystems won't have issues with that. Besides, you can mount a volume directly as read-only, so that not even the FS driver will write to it. –  Mircea Chirea Dec 13 '10 at 12:55
    
@iconiK, mounting read-only relies on the file-system being in a usable state. If data is committed to the buffer, written out of order to the flash, and then fails to commit all the data in the buffer, the superblock could point to garbage, etc... Again, it might work, but I wouldn't be surprised if it was left in a state that was quite unhappy. Certainly, I'm going to continue to have good backups. :-) –  Sean Reifschneider Dec 13 '10 at 20:17
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As a follow up, last weekend we replaced a 8 drive 10K RPM RAID-10 array, which couldn't keep up with the job of acting as an NFS server for e-mail (Maildir) storage and web pages, with a 2.5" Intel 600GB SSD, and performance went way, WAY up. It was amusing to replace that big array with something that fit in my closed hand. –  Sean Reifschneider Jul 7 '11 at 1:23
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durable (comparative more durable, superlative most durable):

able to resist wear, decay; lasting; enduring;

there are several "layers" of truth to what you have heard:

  • you do not have the same amount of write-cycles on a SSD compared to a HDD, so in this aspect HDD wins (as @aking1012 points out correctly, you can only write data so and so often to a single cell in a SSD)
  • you can read from a SSD as much as you want. since no rotating, mechanical things are involved it is likely that a SSD is more durable than a HDD if you only read data from it.
  • you can throw a SSD up into the air, against the wall and .. ok, you can't smash it with a hammer .. but you can put that SSD back into a computer and it still works. under that aspect a HDD is less durable than a SSD

(you could also argue that since a SSD reads data 'faster' it does not have to run as long as a HDD and thus it lasts longer .. aka more durable :))

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Depending on platter density, yes. Really dense platters tend to fail more frequently. SSD has a shelf life from the time you plug it in(data is constantly rotating and each charge cell will eventually stop holding charge)

edit: to clarify...there was a comment that implied i was unclear

SSD does NOT have platters, but has a limited shelf life period

HDD has platters and the denser the platters the more likely they will fail more quickly

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SSDs have platters? –  akira Dec 4 '10 at 16:02
    
no HDD has platters...i thought i was clear i suppose not...clarification in edit –  hbdgaf Dec 4 '10 at 16:09
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For those wondering how many years a typical SSD can last in terms of being able to write data to the number is... about 50 years! So the software or some other hardware is MUCH more likely to fail then your flash cells will wear out.

This is based on simple calculations that typical flash SSD cell can be written 2M times and to write 64GB disk 2M times at maximum speed of 80MB/s you need: (2M x 64GB) / (80MB/s) = (2 x 64G / 80) s = 1.6Gs (which is about 50 years).

Having said that you could probably find less then 1M cycles flash SSD, but haven't seen one.

You can see more details here at SSD endurance summary article by Zsolt Kerekes.

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Unfortunately, some cells will be written to a lot more than others. You cannot assume absolutely even writing, though some drive firmware may try to do that. –  Bob Mar 10 '12 at 11:51
    
That is true, but if a cell is not writeable then the controller will switch to another cell transparently to the system. And so still to make the whole disk unwriteable you would have to write all cells and this is only possible (continuously writing at full speed) after 50 years. Which is not realistic anyway (because you would actually have to have your PC on all the time and have some mad application that would write to your SSD all the time it's on). –  Nux Mar 12 '12 at 10:32
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