Am 01.12.2023 um 12:02 schrieb Corinna Vinschen via Cygwin:
On Dec 1 11:22, Cedric Blancher via Cygwin wrote:
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
For me, it goes up from 1 to 4, then in steps of 4KB.
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
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