On Wed, Apr 19, 2023 at 12:39 PM Nikos Chantziaras <rea...@gmail.com> wrote: > > On 19/04/2023 22:26, Dale wrote: > > So for future reference, let it format with the default? I'm also > > curious if when it creates the file system it will notice this and > > adjust automatically. It might. Maybe? > > AFAIK, SSDs will internally convert to 4096 in their firmware even if > they report a physical sector size of 512 through SMART. Just a > compatibility thing. So formatting with 4096 is fine and gets rid of the > internal conversion.
I suspect this is right, or has been mostly right in the past. I think technically they default to the physical block size internally and the earlier ones, attempting to be more compatible with HDDs, had 4K blocks. Some of the newer chips now have 16K blocks but still support 512B Logical Block Addressing. All of these devices are essentially small computers. They have internal controllers, DRAM caches usually in the 1-2GB sort of range but getting larger. The bus speeds they quote is because data is moving for the most part in and out of cache in the drive. In Dale's case, if he has a 4K file system block size then it's going to send 4K to the drive and the drive will write 8 512 byte writes to put it in flash. If I have the same 4K file system block size I send 4K to the drive but my physical block size is 4K so it's a single write cycle to get it into flash. What I *think* is true is that any time your file system block size is smaller than the physical block size on the storage element then simplistically you have the risk of write amplification. What I know I'm not sure about is how inodes factor into this. For instance: mark@science2:~$ ls -i 35790149 000_NOT_BACKED_UP 33320794 All_Files.txt 33337840 All_Sizes_2.txt 33337952 All_Sizes.txt 33329818 All_Sorted.txt 33306743 ardour_deps_install.sh 33309917 ardour_deps_remove.sh 33557560 Arena_Chess 33423859 Astro_Data 33560973 Astronomy 33423886 Astro_science 33307443 'Backup codes - Login.gov.pdf' 33329080 basic-install.sh 33558634 bin 33561132 biosim4_functions.txt 33316157 Boot_Config.txt 33560975 Builder 33338822 CFL_88_F_Bright_Syn.xsc If the inodes are on the disk then how are they stored? Does a single inode occupy a physical block? A 512 byte LBA? Something else? I have no clue. > > I believe Windows always uses 4096 by default and thus it's reasonable > to assume that most SSDs are aware of that. >
