On Dec 1 11:22, Cedric Blancher via Cygwin wrote: > I see the value of 128k (128*1024 bytes) quite often in your sparse > file commits.
Yes, but they have been removed. Read the patches again, especially commit 65831f88d6c4. > Can you please make this value a per filesystem tunable? No, because we don't have a facility for that. > Not all filesystems have a 128k block/stripe size, and certainly most > filesystems have smaller minimum hole sizes than 128k (e.g. 512bytes > is common, ref pathconf _PC_MIN_HOLE_SIZE). There's no _PC_MIN_HOLE_SIZE in Linux or POSIX. In Windows, a sparse file uses chunks of 64K. You can see this even with a file of just a single block. Try this: $ touch x $ chattr +S x $ echo 1234567890123456789012345678901234567890123456789012345678901234567890123456789 >> x $ ls -ls x 1 -rw-r--r-- 1 corinna vinschen 80 Dec 1 11:56 x [repeat echo and ls -ls until...] $ echo 1234567890123456789012345678901234567890123456789012345678901234567890123456789 >> x $ ls -ls x 1 -rw-r--r-- 1 corinna vinschen 720 Dec 1 11:56 x $ echo 1234567890123456789012345678901234567890123456789012345678901234567890123456789 >> x $ ls -ls x 64 -rw-r--r-- 1 corinna vinschen 800 Dec 1 11:56 x2 ^^ This I don't know how Windows stores short files, maybe they are part of the metadata up to a point or some such. However, as soon as you raise the size over a given point, the *allocation size* will be rounded up to 64K and from that point on, it will be in 64K chunks. Also sparsifying and desparsifying of blocks only works in 64K chunks. Corinna -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
