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Paul Dagnelie 26983d6fa7 Add allocation profile export and zhack subcommand for import
When attempting to debug performance problems on large systems, one of
the major factors that affect performance is free space
fragmentation. This heavily affects the allocation process, which is an
area of active development in ZFS. Unfortunately, fragmenting a large
pool for testing purposes is time consuming; it usually involves filling
the pool and then repeatedly overwriting data until the free space
becomes fragmented, which can take many hours. And even if the time is
available, artificial workloads rarely generate the same fragmentation
patterns as the natural workloads they're attempting to mimic.

This patch has two parts. First, in zdb, we add the ability to export
the full allocation map of the pool. It iterates over each vdev,
printing every allocated segment in the ms_allocatable range tree. This
can be done while the pool is online, though in that case the allocation
map may actually be from several different TXGs as new ones are loaded
on demand.

The second is a new subcommand for zhack, zhack metaslab leak (and its
supporting kernel changes). This is a zhack subcommand that imports a
pool and then modified the range trees of the metaslabs, allowing the
sync process to write them out normall. It does not currently store
those allocations anywhere to make them reversible, and there is no
corresponding free subcommand (which would be extremely dangerous); this
is an irreversible process, only intended for performance testing. The
only way to reclaim the space afterwards is to destroy the pool or roll
back to a checkpoint.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Dagnelie <paul.dagnelie@klarasystems.com>
Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Closes #17576
2025-09-10 15:01:28 -07:00
.github ci: fix syntax issues in zfs-qemu.yml 2025-09-09 17:05:21 -07:00
cmd Add allocation profile export and zhack subcommand for import 2025-09-10 15:01:28 -07:00
config Linux 6.17: d_set_d_op() is no longer available 2025-09-09 17:06:55 -07:00
contrib Add allocation profile export and zhack subcommand for import 2025-09-10 15:01:28 -07:00
etc Add templated zfs-mount@.service 2025-07-03 14:24:07 -07:00
include linux/rw_destroy: assert no holders before destroying 2025-09-10 15:01:02 -07:00
lib linux: use sys/stat.h instead of linux/stat.h 2025-09-09 17:04:15 -07:00
man Add allocation profile export and zhack subcommand for import 2025-09-10 15:01:28 -07:00
module Linux 6.17: d_set_d_op() is no longer available 2025-09-09 17:06:55 -07:00
rpm cmd: rename arcstat to zarcstat 2025-09-10 15:01:20 -07:00
scripts cmd: rename arcstat to zarcstat 2025-09-10 15:01:20 -07:00
tests Add allocation profile export and zhack subcommand for import 2025-09-10 15:01:28 -07:00
udev Update 69-vdev.rules.in 2025-05-21 10:05:11 -07:00
.editorconfig Add an .editorconfig; document git whitespace settings 2020-01-27 13:32:52 -08:00
.gitignore Packaging: Auto-generate changelog during configure (#15528) 2023-11-16 08:58:47 -08:00
.gitmodules .gitmodules: link to openzfs github repository 2021-04-12 09:37:23 -07:00
.mailmap AUTHORS/mailmap: update with new contributors 2025-08-13 15:56:49 -07:00
AUTHORS AUTHORS/mailmap: update with new contributors 2025-08-13 15:56:49 -07:00
autogen.sh Ubuntu 22.04 integration: ShellCheck 2022-11-18 11:24:48 -08:00
CODE_OF_CONDUCT.md Documentation corrections 2022-12-22 11:34:28 -08:00
configure.ac Linux build: handle CONFIG_OBJTOOL_WERROR=y 2025-06-16 08:12:09 -07:00
copy-builtin copy-builtin: add hooks with sed/>> 2022-05-10 10:17:43 -07:00
COPYRIGHT Fix typos 2020-06-09 21:24:09 -07:00
LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
Makefile.am Install zarcstat and zarcsummary symlinks in Makefile 2025-09-09 17:05:30 -07:00
META Tag 2.4.0-rc1 2025-08-22 11:27:48 -07:00
NEWS Fix NEWS file 2020-08-26 21:44:41 -07:00
NOTICE Update build system and packaging 2018-05-29 16:00:33 -07:00
README.md FreeBSD: remove support for FreeBSD < 13.0-RELEASE (#16372) 2024-08-05 16:56:45 -07:00
RELEASES.md Update RELEASES.md LTS release to 2.2 2025-01-17 11:04:36 -05:00
TEST Remove CI builder customization from TEST 2020-03-16 10:46:03 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.

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Official Resources

Installation

Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.

Contribute & Develop

We have a separate document with contribution guidelines.

We have a Code of Conduct.

Release

OpenZFS is released under a CDDL license. For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

  • The META file contains the officially recognized supported Linux kernel versions.
  • Supported FreeBSD versions are any supported branches and releases starting from 13.0-RELEASE.