Taking a Hard Look At SSD Write Endurance 267
New submitter jyujin writes "Ever wonder how long your SSD will last? It's funny how bad people are at estimating just how long '100,000 writes' are going to take when spread over a device that spans several thousand of those blocks over several gigabytes of memory. It obviously gets far worse with newer flash memory that is able to withstand a whopping million writes per cell. So yeah, let's crunch some numbers and fix that misconception. Spoiler: even at the maximum SATA 3.0 link speeds, you'd still find yourself waiting several months or even years for that SSD to start dying on you."
Re:Holy idiocy batman (Score:5, Informative)
100,000? (Score:5, Informative)
100,000 is only for SLC NAND. MLC, what is currently in most SSDs, is only 3,000, and TLC (found in usb drives, samsung 840, and probably more SSDs soon because it's cheaper) is only 1,000.
Is 1,000 fine for most people, yes.. but you should be aware of it. I have a fileserver that writes 200gb per day.. which would kill a Samsung 840 in about 6-7 months.
http://www.anandtech.com/show/6459/samsung-ssd-840-testing-the-endurance-of-tlc-nand [anandtech.com]
Re:Tried It - Disappointed (Score:5, Informative)
Obviious Troll is Obvious but... while SSDs can & do fail (just like old hard drives can & do fail), the reason for SSD failure in the real world is very rarely due to flash memory wear. Hint: If your flash drive suddenly stops working one day, that ain't due to flash wear, which would manifest as gradual failure over time.
Re:Holy idiocy batman (Score:5, Informative)
http://lmgtfy.com/?q=NAND+write+cycles# [lmgtfy.com]
Re:Tried It - Disappointed (Score:5, Informative)
Had an SSD in my laptop for just over a year and a half now, no issues what so ever. Daily use as well.
Re:If SSd is nearly full? (Score:3, Informative)
actually they thought about that never SSD drives have special wear leveling algorithm that if it notices you write some parts a lot and remainder of disk is static they just move static part to used-up space and use underused (ex-static part of disk for writing stuff that changes a lot, more or less you can expect that every cell will be used equal number of times even if you write to just 1 file big 1MB and rest is static
Re:100,000? (AWS?) (Score:4, Informative)
Almost certainly MLC. SLC is really only found in industrial SSDs these days. Enterprise and consumer SSDs are all MLC, with the exception of Samsung 840, the first SSD to use TLC.
Re:Holy idiocy batman (Score:5, Informative)
Re:What about swap? (Score:4, Informative)
I don't expect most servers to swap at all. If your server is swapping, buy more ram. Cell phones are still ram starved enough to need to do that.
Re:100,000? (Score:5, Informative)
I own 2 840s... they are fine. If you're really concerned, samsung has a tool that will let you adjust the spare space.. so you can take a 256gb drive, set aside 20gb to use for spares as cells wear out, and use 236gb for your data.
If you read the article I linked to, an 840 128gb drive will last for about 272TB in writes... or about 11.7 years at 10gb/day.
It's much more likely that another part will wear out before the cells do.
Re:Holy idiocy batman (Score:5, Informative)
Re:Curve or Cliff? (Score:4, Informative)
Sudden failures are controller failures. Especially budget controllers tend to fail before flash does.
Flash failure is "usually" about not being able to write to the disk, but being able to read from the disk. Problem is that when you're getting it, that means you've gone through all the reserve flash and controller no longer has any flash to assign to use from reserve. I.e. drive has been failing for a while.
Modern wear leveling also means that failure would likely cascade very quickly.
Re:Tried It - Disappointed (Score:4, Informative)
My desktop Intel X25 died after 8 months due to running out of spare blocks and an ADATA drive I had in my occasional use laptop lasted about a year and a half. My two anecdotes cancel out your anecdotes.