Status of SSDs under Fedora ?

[Phil Meyer]

On 06/10/2010 03:56 PM, Linuxguy123 wrote:
> On Thu, 2010-06-10 at 14:50 -0700, Konstantin Svist wrote:
>    
>> On 06/10/2010 01:53 PM, Linuxguy123 wrote:
>>      
>>> I'm thinking of getting an Intel 160 GB SSD.   How would it work under
>>> Linux ?
>>>
>>> I'm using ext4 for that drive right now.  Is there a better filesystem
>>> for SSDs ?
>>>
>>> Is there anything that I should be aware of as far as switching ?
>>>
>>>        
> Have you run an SSD ?  Is longevity really an issue or is it folklore ?
>
> Thanks
>
>    

It is bot real and folklore! :)

The fact is that any SSD, or other NAND type device has a limited number 
of writes per address.  The real question is:

"With your data needs and patterns, will you actually need to write to 
the same address over 100,000 times?"

For most people, that is a big fat NO.  The drives are smart enough to 
re-arrange data around failed memory addresses.  So what happens most 
often is a very slight decrease in available space over time.

The advice given is just smart, because most file systems will update 
the same physical disk 'block' containing inode data whenever a file is 
accessed (atime).  The chances of that update hitting the exact address 
every time is quite high.

So, theoretically, if you just read a file on an SSD 100,000 times you 
could destroy a single address location on the SSD.  The device will map 
around it, thus simply dropping available space by one address.  For 
most applications that is no big deal, but for some things that will add 
up very quickly.

So yes, you lose data over time, and you can avoid some of that with 
obvious measures as explained.

So no, with drives in the GB range, who really cares?  Almost no-one.  
When NAND devices were well under 1GB, then yes, it could matter quite a 
bit more.

Not all drives are specifically NAND based, but even the newer 
technologies have a limit on how many times an address can be written 
to, so the principle is the same.

Do you need atimes to be correct for you specific applications?  If not, 
then why not turn them off?

The same is true of the other issues mentioned.

Personally, I have used 2 and 4 GB NAND (the worst type) drives on 
embedded systems for several years (some since 2005). No attempt was 
made to alter atimes or any thing else.  They are still running, and 
still have lots of free space! :)

Your smart phone does the same thing. :)

Good Luck!