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ZFS-REWRITE(8)		    System Manager's Manual		ZFS-REWRITE(8)

NAME
       zfs-rewrite -- rewrite specified	files without modification

SYNOPSIS
       zfs rewrite [-Prvx] [-l length] [-o offset] file|directory

DESCRIPTION
       Rewrite	blocks	of  specified file as is without modification at a new
       location	and possibly with new properties, as if	they  were  atomically
       read  and written back.	See "NOTES".  for more information about prop-
       erty changes that may be	applied	during rewrite.

       -P  Perform physical rewrite, preserving	logical	birth time of  blocks.
	   By  default,	rewrite	updates	logical	birth times, making blocks ap-
	   pear	as modified in snapshots and incremental send streams.	Physi-
	   cal rewrite preserves logical birth times, avoiding unnecessary in-
	   clusion in incremental  streams.   Physical	rewrite	 requires  the
	   physical_rewrite feature to be enabled on the pool.

       -l length
	   Rewrite at most this	number of bytes.

       -o offset
	   Start at this offset	in bytes.

       -r  Recurse into	directories.

       -v  Print names of all successfully rewritten files.

       -x  Don't cross file system mount points	when recursing.

NOTES
       Rewrite	works  by  replacing an	existing block with a new block	of the
       same logical size.  Changed dataset properties that operate on the data
       or metadata without changing the	logical	size will be  applied.	 These
       include checksum, compression, dedup and	copies.	 Changes to properties
       that  affect the	size of	a logical block, like recordsize, will have no
       effect.

       Rewrite of cloned blocks	and blocks that	are  part  of  any  snapshots,
       same  as	 some  property	 changes may increase pool space usage.	 Holes
       that were never written or  were	 previously  zero-compressed  are  not
       rewritten and will remain holes even if compression is disabled.

       If  a  -l  or -o	value request a	rewrite	to regions past	the end	of the
       file, then those	regions	are silently ignored,  and  no	error  is  re-
       ported.

       By  default,  rewritten blocks update their logical birth time, meaning
       they will be included in	incremental zfs	send streams as	modified data.
       When the	-P flag	is used, rewritten blocks preserve their logical birth
       time, since there are no	user data changes.

SEE ALSO
       zfsprops(7), zpool-features(7)

FreeBSD	ports 15.quarterly     November	5, 2025			ZFS-REWRITE(8)

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