On 07.11.2017 01:43, Michael Stone wrote:
On Tue, Nov 07, 2017 at 01:00:54AM +0500, Alexander V. Makartsev wrote:As I know SSDs are different in a way HDDs write their data. HDDs write directly to the free block and are done. SSDs on the other hand will have to erase free block first to get it ready for writing and then write to it. This is because how NAND work. It's even worse, if a destination block has some data on it already and there is some data needs to be written onto it, then SSD will copy data already written, then it will fully erase destination block, then it will concatenate copied data with data to be written and finally will write merged data to the block.
TRIM will erase blocks marked as deleted beforehand even if they are not needed for writing right now. This overhead is the reason that causes increased drive wear and decrease it's lifespan.
I do agree, that using fstune manually once in say half a year on a non busy SSD could improve writing performance for some time, but using discard or equivalent permanently in fstab is hardly worth it.
-- With kindest regards, Alexander. ⢀⣴⠾⠻⢶⣦⠀ ⣾⠁⢠⠒⠀⣿⡁ Debian - The universal operating system ⢿⡄⠘⠷⠚⠋⠀ https://www.debian.org ⠈⠳⣄⠀⠀⠀⠀