Please see git logs for detailed change log.
This file just contains highlight.
Changes Prior to release 3.3
- Some array reshapes can proceed without needing backup file.
This is done by changing the 'data_offset' so we never need to write
any data back over where it was before. If there is no "head space"
or "tail space" to allow data_offset to change, the old mechanism
with a backup file can still be used.
- RAID10 arrays can be reshaped to change the number of devices,
change the chunk size, or change the layout between 'near'
This will always change data_offset, and will fail if there is no
room for data_offset to be moved.
- "--assemble --update=metadata" can convert a 0.90 array to a 1.0 array.
- bad-block-logs are supported (but not heavily tested yet)
- "--assemble --update=revert-reshape" can be used to undo a reshape
that has just been started but isn't really wanted. This is very
new and while it passes basic tests it cannot be guaranteed.
- improved locking between --incremental and --assemble
- uses systemd to run "mdmon" if systemd is configured to do that.
- kernel names of md devices can be non-numeric. e.g. "md_home" rather than
"md0". This will probably confuse lots of other tools, so you need to
echo CREATE names=yes >> /etc/mdadm.conf
or the feature will not be used. (you also need a reasonably new kernel).
- "--stop" can be given a kernel name instead of a device name. i.e
mdadm --stop md4
will work even if /dev/md4 doesn't exist.
- "--detail --export" has some information about the devices in the array
- --dump and --restore can be used to backup and restore the metadata on an
- Hot-replace is supported with
mdadm /dev/mdX --replace /dev/foo
mdadm /dev/mdX --replace /dev/foo --with /dev/bar
- Config file can be a directory in which case all "*.conf" files are
read in lexical order.
Default is to read /etc/mdadm.conf and then /etc/mdadm.conf.d
echo CREATE name=yes > /etc/mdadm.conf.d/names.conf
will also enable the use of named md devices.
- Lots of improvements to DDF support including adding support for
RAID10 (thanks Martin Wilck).
Changes Prior to release 3.2.6
- There are no real stand-out fixes, just lots of little bits and pieces.
Changes Prior to release 3.2.5
- This release primarily fixes a serious regression in 3.2.4.
This regression does *not* cause any risk to data. It simply
means that adding a device with "--add" would sometime fail
when it should not.
- The fix also includes a couple of minor fixes such as making
the "--layout=preserve" option to "--grow" work again.
Changes Prior to release 3.2.4
"--oneline" log of changes is below. Some notable ones are:
- --offroot argument to improve interactions between mdmon and initrd
- --prefer argument to select which /dev names to display in some
- relax restructions on when "--add" will be allowed
- Fix bug with adding write-intent-bitmap to active array
- Now defaults to "/run/mdadm" for storing run-time files.
Changes Prior to release 3.2.3
- The largest single area of change is support for reshape of Intel
IMSM arrays (OnLine Capacity Explansion and Level Migration).
- Among other fixes, this now has a better chance of surviving if a
device fails during reshape.
Changes Prior to release 3.2.2
- reshaping IMSM (Intel metadata) arrays is no longer 'experimental',
it should work properly and be largely compatible with IMSM drivers in
- --assume-clean can be used with --grow --size to avoid resyncing the
new part of the array. This is only support with very new kernels.
- RAID0 arrays can have chunksize which is not a power of 2. This has been
supported in the kernel for a while but is only now supprted by
- A new tool 'raid6check' is available which can check a RAID6 array,
or part of it, and report which device is most inconsistent with the
others if any stripe is inconsistent. This is still under development
and does not have a man page yet. If anyone tries it out and has any
questions or experience to report, they would be most welcome on
Changes Prior to release 3.2.1
- policy framework
Policy can be expressed for moving spare devices between arrays, and
for how to handle hot-plugged devices. This policy can be different
for devices plugged in to different controllers etc.
This, for example, allows a configuration where when a device is plugged
in it is immediately included in an md array as a hot spare and
possibly starts recovery immediately if an array is degraded.
- some understanding of mbr and gpt paritition tables
This is primarly to support the new hot-plug support. If a
device is plugged in and policy suggests it should have a partition table,
the partition table will be copied from a suitably similar device, and
then the partitions will hot-plug and can then be added to md arrays.
- "--incremental --remove" can remember where a device was removed from
so if a device gets plugged back in the same place, special policy applies
to it, allowing it to be included in an array even if a general hotplug
will not be included.
- enhanced reshape options, including growing a RAID0 by converting to RAID4,
restriping, and converting back. Also convertions between RAID0 and
RAID10 and between RAID1 and RAID10 are possible (with a suitably recent
- spare migration for IMSM arrays.
Spare migration can now work across 'containers' using non-native metadata
and specifically Intel's IMSM arrays support spare migrations.
- OLCE and level migration for Intel IMSM arrays.
OnLine Capacity Expansion and level migration (e.g. RAID0 -> RAID5) is
supported for Intel Matrix Storage Manager arrays.
This support is currently 'experimental' for technical reasons. It can
be enabled with "export MDADM_EXPERIMENTAL=1"
- avoid including wayward devices
If you split a RAID1, mount the two halves as two separate degraded RAID1s,
and then later bring the two back together, it is possible that the md
metadata won't properly show that one must over-ride the other.
mdadm now does extra checking to detect this possibilty and avoid
potentially corrupting data.
- remove any possible confusion between similar options.
e.g. --brief and --bitmap were mapped to 'b' and mdadm wouldn't
notice if one was used where the other was expected.
- allow K,M,G suffixes on chunk sizes
Changes Prior to release 3.2
- By far the most significant change in this release related to the
management of reshaping arrays. This code has been substantially
re-written so that it can work with 'externally managed metadata' -
Intel's IMSM in particular. We now support level migration and
OnLine Capacity Expansion on these arrays.
- Policy framework.
Various policy statements can be made in the mdadm.conf to guide
the behaviour of mdadm, particular with regards to how new devices
are treated by "mdadm -I".
Depending on the 'action' associated with a device (identified by
its 'path') such need devices can be automatically re-added to and
existing array that they previously fell out off, or automatically
added as a spare if they appear to contain no data.
- mdadm now has a limited understanding of partition tables. This
allows the policy framework to make decisions about partitioned
devices as well.
- --incremental --remove can be told what --path the device was on,
and this info will be recorded so that another device appearing at
the same physical location can be preferentially added to the same
array (provides the spare-same-slot action policy applied to the
- A new flags "--invalid-backup" flag is available in --assemble
mode. This can be used to re-assemble an array which was stopping
in the middle of a reshape, and for which the 'backup file' is no
longer available or is corrupted. The array may have some
corruption in it at the point where reshape was up to, but at least
the rest of the array will become available.
- Various internal restructuring - more is needed.
Changes Prior to release 3.1.5
- Fixes for v1.x metadata on big-endian machines.
- man page improvements
- Improve '--detail --export' when run on partitions of an md array.
- Fix regression with removing 'failed' or 'detached' devices.
- Fixes for "--assemble --force" in various unusual cases.
- Allow '-Y' to mean --export. This was documented but not implemented.
- Various fixed for handling 'ddf' metadata. This is now more reliable
but could benefit from more interoperability testing.
- Correctly list subarrays of a container in "--detail" output.
- Improve checks on whether the requested number of devices is supported
by the metadata - both for --create and --grow.
- Don't remove partitions from a device that is being included in an
array until we are fully committed to including it.
- Allow "--assemble --update=no-bitmap" so an array with a corrupt
bitmap can still be assembled.
- Don't allow --add to succeed if it looks like a "--re-add" is probably
wanted, but cannot succeed. This avoids inadvertently turning
devices into spares when an array is failed.
Changes Prior to release 3.1.4
Two fixes related to configs that aren't using udev:
- Don't remove md devices which 'standard' names on --stop
- Allow dev_open to work on read-only /dev
And fixed regressions:
- Allow --incremental to add spares to an array
- Accept --no-degraded as a deprecated option rather than
throwing an error
- Return correct success status when --incrmental assembling
a container which does not yet have enough devices.
- Don't link mdadm with pthreads, only mdmon needs it.
- Fix compiler warning due to bad use of snprintf
Changes Prior to release 3.1.3
- mapfile now lives in a fixed location which default to
/dev/.mdadm/map but can be changed at compile time. This
location is choses and most distros provide it during early
boot and preserve it through. As long a /dev exists and is
writable, /dev/.mdadm will be created.
Other files file communication with mdmon live here too.
This fixes a bug reported by Debian and Gentoo users where
udev would spin in early-boot.
- IMSM and DDF metadata will not be recognised on partitions
as they should only be used on whole-disks.
- Various overflows causes by 2G drives have been addressed.
- A subarray of an IMSM contain can now be killed with
--kill-subarray. Also subarrays can be renamed with
- -If (or --incremental --fail) can be used from udev to
fail and remove from all arrays a device which has been
unplugged from the system. i.e. hot-unplug-support.
- "mdadm /dev/mdX --re-add missing" will look for any device
that looks like it should be a member of /dev/mdX but isn't
and will automatically --re-add it
- Now compile with -Wextra to get extra warnings.
- Lots of minor bug fixes, documentation improvements, etcc
Changes Prior to release 3.1.2
- The default metadata has change again (sorry about that).
It is now v1.2 and will hopefully stay that way. It turned
out there with boot-block issues with v1.1 which make it
unsuitable for a default, though in many cases it is still
suitable to use.
- Stopping a container is not permitted when members are still
- Add 'homehost' to the valid words for the "AUTO" config file
line. When followed by "-all", this causes mdadm to
auto-assemble any array belonging to this host, but not
auto-assemble anything else.
- Fix some bugs with "--grow --chunksize=" for changing chunksize.
- VAR_RUN can be easily changed at compile time just like ALT_RUN.
This gives distros more flexability in how to manage the
pid and sock files that mdmon needs.
- Various mdmon fixes
- Alway make bitmap 4K-aligned if at all possible.
- If mdadm.conf lists arrays which have inter-dependencies,
the previously had to be listed in the "right" order. Now
any order should work.
- Fix --force assembly of v1.x arrays which are in the process
- Add section on 'scrubbing' to 'md' man page.
- Various command-line-option parsing improvements.
- ... and lots of other bug fixes.
Changes Prior to release 3.1.1
- Multiple fixes for new --grow levels including fixes for
serious data corruption problems.
- Change default metadata to v1.1
- Change default chunk size to 512K
- Change default bitmap chunk size to 64Meg
- When --re-add is used, don't fall back to
--add if --re-add fails as this can destroy data.
Changes Prior to release 3.1
- Support --grow to change the layout of RAID4/5/6
- Support --grow to change the chunksize of raid 4/5/6
- Support --grow to change level from RAID1 -> RAID5 -> RAID6 and
- Support --grow to reduce the number of devices in RAID4/5/6.
- Support restart of these grow options which assembling an array
which is partially grown.
- Assorted tests of this code, and of different RAID6 layouts.
Changes Prior to release 3.0.3
- Improvements for creating arrays giving just a name, like 'foo',
rather than the full '/dev/md/foo'.
- Improvements for assembling member arrays of containers.
- Improvements to test suite
- Add option to change increment for RebuildNN messages reported
by "mdadm --monitor"
- Improvements to mdmon 'hand-over' from initrd to final root.
- Handle merging of devices that have left an IMSM array and are
- Add missing space in "--detail --brief" output.
Changes Prior to release 3.0.2
- Fix crash when hosthost is not set, as often happens in
Changes Prior to release 3.0.1
- Fix various segfaults
- Fixed for --examine with containers
- Lots of other little fixes.
Changes Prior to release 3.0
- Support for externally managed metadata, specifically DDF and IMSM.
- Depend on udev to create entries in /dev, rather than creating them
- remove --auto-update-home-hosts
- new config file line "auto"
- new "<ignore>" and "any" options for "homehost"
- numerous bug fixes and minor enhancements.