Christian Seiler a écrit : > On 01/08/2016 02:51 AM, Pascal Hambourg wrote: >> Current tools won't align for compatibility purpose any more. The >> default 1-MiB alignment is only for performance purpose, not compatibility. > > This is new to me - I always thought that this was entirely for > compatibility. I'm curious: How would that help performance-wise? > On SSDs it shouldn't matter at all - and if you have rotational > media, you'd need to figure out the physical (not the logical) > geometry of the drive to be effective - and if I'm not mistaken > there's no standardized way of getting to that via software. What > am I missing here?
The real physical geometry does not matter at all. What matters is only the physical read/write/erase block size. You get a read-modify-write penalty if you don't align write operations on proper block boundaries. 1 MiB was chosen as a multiple of all common block sizes for both SSD and 512e "Advanced Format" hard disks. See for example <https://en.wikipedia.org/wiki/Solid-state_drive#File_systems_suitable_for_SSDs> <https://en.wikipedia.org/wiki/Advanced_Format#512e>
