On 2023-02-16 at 05:45, Nicolas George wrote: > DdB (12023-02-16): > >> Am 16.02.2023 um 09:31 schrieb Felix Miata: >> > None of the 25 or so SSDs/NVMEs I have have 4k sectors. e.g. >> >> Wow, they must be rather old, then. ;-) >> >> I know, i am not the only one ... >> https://serverfault.com/questions/1113068/how-to-find-page-size-of-my-ssd > > Of course you are not the only one. But the real answer was to be found > in another random stackoverflow forum: > > When you have 512 octets logical sectors and 4096 octets physical > sectors, you really have eight logical sectors in a physical one, it > matters to align the small ones inside the big ones. > > But with blocks of flash memory, there is not constant nor regular > mapping of sectors to blocks, so the information about the block size is > not useful outside of the disk controller. I'm already confused by the way terminology is being used in this conversation (and I wouldn't be surprised I wasn't the only one), but this is just "huh?" to me. My understanding is that with SSDs it's even *more* important to keep filesystems et cetera aligned to physical blocks, because physical block size defines the minimum size that can be erased (and, therefore, overwritten) in any given operation, and therefore impacts both wear rates and write speeds in what is potentially a very serious way. The way I interpret what I read you as having written, here, is that on the contrary block sizes can be completely disregarded because the disk controller will handle all of that alignment stuff internally. This being the very first time I can remember having encountered even the suggestion that there's no need to be concerned about erase-block sizes when dealing with SSDs et cetera, I hope it's understandable that I'd want to get things clarified. -- The Wanderer The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. -- George Bernard Shaw
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