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linux-next/Documentation/device-mapper
Jonthan Brassow f5db4af466 dm raid1: add userspace log
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>
2009-06-22 10:12:35 +01:00
..
delay.txt dm: delay target 2007-05-09 12:30:47 -07:00
dm-crypt.txt dm crypt: add documentation 2008-04-25 13:27:03 +01:00
dm-io.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
dm-log.txt dm raid1: add userspace log 2009-06-22 10:12:35 +01:00
dm-queue-length.txt dm mpath: add queue length load balancer 2009-06-22 10:12:27 +01:00
dm-service-time.txt dm mpath: add service time load balancer 2009-06-22 10:12:28 +01:00
dm-uevent.txt dm: uevent generate events 2007-10-20 02:01:26 +01:00
kcopyd.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
linear.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
snapshot.txt [PATCH] Fix dm-snapshot tutorial in Documentation 2005-11-07 07:53:54 -08:00
striped.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
zero.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00