1.\" SPDX-License-Identifier: CDDL-1.0 2.\" 3.\" CDDL HEADER START 4.\" 5.\" The contents of this file are subject to the terms of the 6.\" Common Development and Distribution License (the "License"). 7.\" You may not use this file except in compliance with the License. 8.\" 9.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10.\" or https://opensource.org/licenses/CDDL-1.0. 11.\" See the License for the specific language governing permissions 12.\" and limitations under the License. 13.\" 14.\" When distributing Covered Code, include this CDDL HEADER in each 15.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16.\" If applicable, add the following below this CDDL HEADER, with the 17.\" fields enclosed by brackets "[]" replaced with your own identifying 18.\" information: Portions Copyright [yyyy] [name of copyright owner] 19.\" 20.\" CDDL HEADER END 21.\" 22.\" Copyright (c) 2025 iXsystems, Inc. 23.\" 24.Dd May 6, 2025 25.Dt ZFS-REWRITE 8 26.Os 27. 28.Sh NAME 29.Nm zfs-rewrite 30.Nd rewrite specified files without modification 31.Sh SYNOPSIS 32.Nm zfs 33.Cm rewrite 34.Oo Fl Prvx Ns Oc 35.Op Fl l Ar length 36.Op Fl o Ar offset 37.Ar file Ns | Ns Ar directory Ns … 38. 39.Sh DESCRIPTION 40Rewrite blocks of specified 41.Ar file 42as is without modification at a new location and possibly with new 43properties, such as checksum, compression, dedup, copies, etc, 44as if they were atomically read and written back. 45.Bl -tag -width "-r" 46.It Fl P 47Perform physical rewrite, preserving logical birth time of blocks. 48By default, rewrite updates logical birth times, making blocks appear 49as modified in snapshots and incremental send streams. 50Physical rewrite preserves logical birth times, avoiding unnecessary 51inclusion in incremental streams. 52Physical rewrite requires the 53.Sy physical_rewrite 54feature to be enabled on the pool. 55.It Fl l Ar length 56Rewrite at most this number of bytes. 57.It Fl o Ar offset 58Start at this offset in bytes. 59.It Fl r 60Recurse into directories. 61.It Fl v 62Print names of all successfully rewritten files. 63.It Fl x 64Don't cross file system mount points when recursing. 65.El 66.Sh NOTES 67Rewrite of cloned blocks and blocks that are part of any snapshots, 68same as some property changes may increase pool space usage. 69Holes that were never written or were previously zero-compressed are 70not rewritten and will remain holes even if compression is disabled. 71.Pp 72If a 73.Fl l 74or 75.Fl o 76value request a rewrite to regions past the end of the file, then those 77regions are silently ignored, and no error is reported. 78.Pp 79By default, rewritten blocks update their logical birth time, 80meaning they will be included in incremental 81.Nm zfs Cm send 82streams as modified data. 83When the 84.Fl P 85flag is used, rewritten blocks preserve their logical birth time, since 86there are no user data changes. 87. 88.Sh SEE ALSO 89.Xr zfsprops 7 , 90.Xr zpool-features 7 91