Re:Apple Silicon Macs can't boot from external drive if inte...
by wtallis on Tuesday November 02, 2021 @02:52PM
(#29085803)
> You can't wear-level against blocks that are in use, only blocks that are free.
It only takes a bit of arithmetic to prove that this cannot possibly be true, or else all of those 95%-full drives would have long since failed, and QLC SSDs would have been a disaster and never would have been adopted by system OEMs that provide multi-year warranties. (And if it were true, then SSDs prior to TRIM wouldn't have been viable.)
You can include static data in wear leveling, and all SSDs do. It does lead to some write amplification, but that's already factored in to a drive's endurance specs.
Re:Apple Silicon Macs can't boot from external drive if inte...
by 1123581321 on Tuesday November 02, 2021 @02:39PM
(#29085605)
I did not say SSD wear works that way. All of that is factored into the usage I cited—-swap, system writes, etc. do not wear the drive as much as you appear to think for most users.
You can't wear-level against blocks that are in use, only blocks that are free.
If every person I've helped socially and professionally is any indication, people keep their storage anywhere between 80% and 95% full.
At 95% full, all your write cycles are focused on just 5% (plus spare provisioned blocks.)
Think about how browsers consume all available memory and then readily push the system into using a lot of swap. I have to restart my browser regularly because of how much ram it uses even if I've closed every tab.
Think about how whole-system file content indexing is the norm, and all the write operations that occur every time a file is added or updated.
Think about how a lot of applications are just electron apps and they routinely update themselves.
Think about all the filesystem metadata changes.
Etc.