"jeff.liu" <jeff....@oracle.com> wrote:
> Hello List,
>
> I am trying to fetch the data/hole info of a sparse file through the
> lseek(SEEK_HOLE/SEEK_DATA)
> stuff, the result of fpathconf(..., _PC_MIN_HOLE_SIZE) is ok, so I think this
> interface is supported
> on my testing ZFS, but SEEK_HOLE always return the sparse file total size
> instead of the desired
> first hole start offset.
Maybe you did not create the file correctly.
If you like to create a file of a specific size that only contains one single
hole, there is a way to do this using star:
mkfile <size> some-file # create a file of the desired size
star -c f=xx.tar -meta some-file # archive the meta data only
rm some-file # remove original file
star -x -xmeta -force-hole f=xx.tar # let star create an empty file of the
# same size
This will try to create a file that has one hole but no data in case the
filesystem supports to do this.
For UFS, such a file e.g. needs to be a multiple of 8k in size. This is because
holes in UFS need to be aligned at 8k boundaries and need to be a multiple of
8k in size.
A recent star can be found in the schily source consolidation:
ftp://ftp.berlios.de/pub/schily/
star is part of Schillix-ON (a free OpenSolaris fork).
Jörg
--
EMail:jo...@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
j...@cs.tu-berlin.de (uni)
joerg.schill...@fokus.fraunhofer.de (work) Blog:
http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/private/ ftp://ftp.berlios.de/pub/schily
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
