This target is the same as the linear target except that it returns I/O
errors periodically. It's been found useful in simulating failing
devices for testing purposes.
I needed a dm target to do some failure testing on btrfs's raid code, and
Mike pointed me at this.
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This patch is the skeleton for the DM target that will be
the bridge from DM to MD (initially RAID456 and later RAID1). It
provides a way to use device-mapper interfaces to the MD RAID456
drivers.
As with all device-mapper targets, the nominal public interfaces are the
constructor (CTR) tables and the status outputs (both STATUSTYPE_INFO
and STATUSTYPE_TABLE). The CTR table looks like the following:
1: <s> <l> raid \
2: <raid_type> <#raid_params> <raid_params> \
3: <#raid_devs> <meta_dev1> <dev1> .. <meta_devN> <devN>
Line 1 contains the standard first three arguments to any device-mapper
target - the start, length, and target type fields. The target type in
this case is "raid".
Line 2 contains the arguments that define the particular raid
type/personality/level, the required arguments for that raid type, and
any optional arguments. Possible raid types include: raid4, raid5_la,
raid5_ls, raid5_rs, raid6_zr, raid6_nr, and raid6_nc. (again, raid1 is
planned for the future.) The list of required and optional parameters
is the same for all the current raid types. The required parameters are
positional, while the optional parameters are given as key/value pairs.
The possible parameters are as follows:
<chunk_size> Chunk size in sectors.
[[no]sync] Force/Prevent RAID initialization
[rebuild <idx>] Rebuild the drive indicated by the index
[daemon_sleep <ms>] Time between bitmap daemon work to clear bits
[min_recovery_rate <kB/sec/disk>] Throttle RAID initialization
[max_recovery_rate <kB/sec/disk>] Throttle RAID initialization
[max_write_behind <value>] See '-write-behind=' (man mdadm)
[stripe_cache <sectors>] Stripe cache size for higher RAIDs
Line 3 contains the list of devices that compose the array in
metadata/data device pairs. If the metadata is stored separately, a '-'
is given for the metadata device position. If a drive has failed or is
missing at creation time, a '-' can be given for both the metadata and
data drives for a given position.
Examples:
# RAID4 - 4 data drives, 1 parity
# No metadata devices specified to hold superblock/bitmap info
# Chunk size of 1MiB
# (Lines separated for easy reading)
0 1960893648 raid \
raid4 1 2048 \
5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81
# RAID4 - 4 data drives, 1 parity (no metadata devices)
# Chunk size of 1MiB, force RAID initialization,
# min recovery rate at 20 kiB/sec/disk
0 1960893648 raid \
raid4 4 2048 min_recovery_rate 20 sync\
5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81
Performing a 'dmsetup table' should display the CTR table used to
construct the mapping (with possible reordering of optional
parameters).
Performing a 'dmsetup status' will yield information on the state and
health of the array. The output is as follows:
1: <s> <l> raid \
2: <raid_type> <#devices> <1 health char for each dev> <resync_ratio>
Line 1 is standard DM output. Line 2 is best shown by example:
0 1960893648 raid raid4 5 AAAAA 2/490221568
Here we can see the RAID type is raid4, there are 5 devices - all of
which are 'A'live, and the array is 2/490221568 complete with recovery.
Cc: linux-raid@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This patch adds generic multikey handling to be used
in following patch for Loop-AES mode compatibility.
This patch extends mapping table to optional keycount and
implements generic multi-key capability.
With more keys defined the <key> string is divided into
several <keycount> sections and these are used for tfms.
The tfm is used according to sector offset
(sector 0->tfm[0], sector 1->tfm[1], sector N->tfm[N modulo keycount])
(only power of two values supported for keycount here).
Because of tfms per-cpu allocation, this mode can be take
a lot of memory on large smp systems.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Max Vozeler <max@hinterhof.net>
Below you will find an updated version from the original series bunching all patches into one big patch
updating broken web addresses that are located in Documentation/*
Some of the addresses date as far far back as 1995 etc... so searching became a bit difficult,
the best way to deal with these is to use web.archive.org to locate these addresses that are outdated.
Now there are also some addresses pointing to .spec files some are located, but some(after searching
on the companies site)where still no where to be found. In this case I just changed the address
to the company site this way the users can contact the company and they can locate them for the users.
Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: Thomas Weber <weber@corscience.de>
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Cc: Paulo Marques <pmarques@grupopie.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Michael Neuling <mikey@neuling.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Update Documentation/device-mapper/snapshot.txt to cover "How to
determine when a snapshot has finished merging".
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
The snapshot-merge target allows a snapshot to be merged back into the
snapshot's origin device.
One anticipated use of snapshot merging is the rollback of filesystems
to back out problematic system upgrades.
This patch adds snapshot-merge target management to both
dm_snapshot_init() and dm_snapshot_exit(). As an initial place-holder,
snapshot-merge is identical to the snapshot target. Documentation is
provided.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This patch contains a device-mapper mirror log module that forwards
requests to userspace for processing.
The structures used for communication between kernel and userspace are
located in include/linux/dm-log-userspace.h. Due to the frequency,
diversity, and 2-way communication nature of the exchanges between
kernel and userspace, 'connector' was chosen as the interface for
communication.
The first log implementations written in userspace - "clustered-disk"
and "clustered-core" - support clustered shared storage. A userspace
daemon (in the LVM2 source code repository) uses openAIS/corosync to
process requests in an ordered fashion with the rest of the nodes in the
cluster so as to prevent log state corruption. Other implementations
with no association to LVM or openAIS/corosync, are certainly possible.
(Imagine if two machines are writing to the same region of a mirror.
They would both mark the region dirty, but you need a cluster-aware
entity that can handle properly marking the region clean when they are
done. Otherwise, you might clear the region when the first machine is
done, not the second.)
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This patch adds a service time oriented dynamic load balancer,
dm-service-time, which selects the path with the shortest estimated
service time for the incoming I/O.
The service time is estimated by dividing the in-flight I/O size
by a performance value of each path.
The performance value can be given as a table argument at the table
loading time. If no performance value is given, all paths are
considered equal.
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This patch adds a dynamic load balancer, dm-queue-length, which
balances the number of in-flight I/Os across the paths.
The code is based on the patch posted by Stefan Bader:
https://www.redhat.com/archives/dm-devel/2005-October/msg00050.html
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Add description of dm-crypt to device-mapper documentation.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This patch adds support for the dm_path_event dm_send_event functions which
create and send udev events.
Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
New device-mapper target that can delay I/O (for testing). Reads can be
separated from writes, redirected to different underlying devices and delayed
by differing amounts of time.
Signed-off-by: Heinz Mauelshagen <mauelshagen@redhat.com>
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I've recently added this documentation, Alasdair gave some corrections, and
here are some further corrections on top of his work (partly style issue,
partly a technical error due to different past experience, partly a note
which I've added - i.e. transient snapshots are lighter).
Cc: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
I've recently discovered the real functionality of device-mapper snapshots,
and since they are not well known, I've decided to write some docs for
them.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
