On Mon, 10 Jul 2023 at 10:06, Martin Husemann <mar...@duskware.de> wrote: > > On Sun, Jul 09, 2023 at 08:54:56PM +0100, David Brownlee wrote: > > In practice I think it would be better not to penalise current use of > > "small" (120GB SSD or 64GB or or CF/USB devices) for an edge case of > > older hardware > > I am not sure what you see as penalty here.
An offset of 63 sectors is guaranteed to be non-optimal for any device with larger than 512 byte internal block size. As such it's likely a poor choice for any solid state storage, and potentially some traditional disks (though any of the latter with > 512 byte sectors are almost certainly > 128GB and so avoid the behaviour). > I think two factors made the original size decisions sensible back then: > > - for large disks the space lost to alignment does not matter > - native block sizes > 512 byte only happened for larger disks initially > > Overall it would be better to enforce alignment as least as large as the > native block size on *any* disk - but IIRC it is quite hard to find that > value in all cases. We currently effectively have two values - 63 sectors and 1MB. We have the cutoff between them at 128GB. I propose moving that to 2GB, to gain the more optimal alignment on devices from 2GB to 128GB. Thanks David
