Ssd wear when full?

[Cyber-Mav]

If a ssd is full of data e.g 500mb free space left can it still wear level or does its entire endurance level drop? E.g if its full and your just writing to empty spaces will it wear out those sectors faster?
I get that write performance tanks when its full

 

[EsaT]

That write performance tanking is precisely related also to why wear increases:
Flash can be written only in certain size chunks.
And if that small remaining free space is in small pieces spread over lots of those blocks, drive has to write more data than actual stored file.
(first reading existing data inside block and then emptying block before writing with new added data)

 

[Cyber-Mav]

i get the write amplification part and how trim works but what i dont get is if you got your basic install done e.g 300 gigs of 500gig drive used then is it just the remaining 200gigs thats used for subsequent writes and wear leveling across those 200 remaining gigs takes place? so does the at 200gb free space area wear out faster since the 300gb used by untouched data such as films is still on its first write cycle?
i dont think these drives are smart enough or if its even possible for them to shift data around internally to wear all sectors evenly?
any ideas?

 

[Semple]

i get the write amplification part and how trim works but what i dont get is if you got your basic install done e.g 300 gigs of 500gig drive used then is it just the remaining 200gigs thats used for subsequent writes and wear leveling across those 200 remaining gigs takes place? so does the at 200gb free space area wear out faster since the 300gb used by untouched data such as films is still on its first write cycle?
i dont think these drives are smart enough or if its even possible for them to shift data around internally to wear all sectors evenly?
any ideas?

Those 300gb of cells would be more prone to bit rot though.

 

[Cyber-Mav]

Yep on bit rot. I found a big tech document from micron explaining how wear leveling works quick skip through it shows it answers what i was asking. Just gonna make some time to go through it all

 

[EsaT]

so does the at 200gb free space area wear out faster since the 300gb used by untouched data such as films is still on its first write cycle?

Wear leveling takes also cells used by static data into reuse for changing data.
Which incidentally creates also once more writes from moving that static data to cells which have been written more times.

Because of that there's simply no relation in file system level block adresses of the files to location of actual data on Flash cells.

Also controller propbably once in a while checks Flash cell charge states in case data needs refresh write because of charge starting to degrade.
After Samsung's planar TLC fiasco and "fix" by regular rewrites would expect everyone to have looked into that to increase reliability.

 

[Rroff]

Samsung encourages you to enable over provisioning to improve lifespan of the SSD and I think a certain amount of that is done internally as well to improve the situation.

 

[Phil2008]

The reason why you should leave free space on a ssd,, is so the same cells are not being written on continuously, increasing the lifespan of the drive.

I had my 120gb ssd for about 3-5yrs now and its only just over half full, so theres plenty of cells for it to use.. I dont use the "over provisioning" because it just stops you from filling up the drive.