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.\" Copyright (c) 2025 iXsystems, Inc.
.\"
.Dd May 6, 2025
.Dt ZFS-REWRITE 8
.Os
.
.Sh NAME
.Nm zfs-rewrite
.Nd rewrite specified files without modification
.Sh SYNOPSIS
.Nm zfs
.Cm rewrite
.Oo Fl rvx Ns Oc
.Op Fl l Ar length
.Op Fl o Ar offset
.Ar file Ns | Ns Ar directory Ns …
.
.Sh DESCRIPTION
Rewrite blocks of specified
.Ar file
as is without modification at a new location and possibly with new
properties, such as checksum, compression, dedup, copies, etc,
as if they were atomically read and written back.
.Bl -tag -width "-r"
.It Fl l Ar length
Rewrite at most this number of bytes.
.It Fl o Ar offset
Start at this offset in bytes.
.It Fl r
Recurse into directories.
.It Fl v
Print names of all successfully rewritten files.
.It Fl x
Don't cross file system mount points when recursing.
.El
.Sh NOTES
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.
.Pp
Rewritten blocks will be seen as modified in next snapshot and as such
included into the incremental
.Nm zfs Cm send
stream.
.Pp
If a
.Fl l
or
.Fl o
value request a rewrite to regions past the end of the file, then those
regions are silently ignored, and no error is reported.
.
.Sh SEE ALSO
.Xr zfsprops 7