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authorJonathan Brassow <jbrassow@redhat.com>2011-08-02 15:32:07 +0400
committerAlasdair G Kergon <agk@redhat.com>2011-08-02 15:32:07 +0400
commitb12d437b73d32203a41fde0d407e91812c866844 (patch)
tree3c7a33f4a45779da4a5edb71678ce7f8ae4169e7 /drivers/md/Kconfig
parent46bed2b5c16bb7c82e1088d7ae75fb958c8a8c4e (diff)
downloadlinux-b12d437b73d32203a41fde0d407e91812c866844.tar.xz
dm raid: support metadata devices
Add the ability to parse and use metadata devices to dm-raid. Although not strictly required, without the metadata devices, many features of RAID are unavailable. They are used to store a superblock and bitmap. The role, or position in the array, of each device must be recorded in its superblock. This is to help with fault handling, array reshaping, and sanity checks. RAID 4/5/6 devices must be loaded in a specific order: in this way, the 'array_position' field helps validate the correctness of the mapping when it is loaded. It can be used during reshaping to identify which devices are added/removed. Fault handling is impossible without this field. For example, when a device fails it is recorded in the superblock. If this is a RAID1 device and the offending device is removed from the array, there must be a way during subsequent array assembly to determine that the failed device was the one removed. This is done by correlating the 'array_position' field and the bit-field variable 'failed_devices'. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/Kconfig')
-rw-r--r--drivers/md/Kconfig5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 8420129fc5ee..f75a66e7d312 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -241,12 +241,13 @@ config DM_MIRROR
needed for live data migration tools such as 'pvmove'.
config DM_RAID
- tristate "RAID 4/5/6 target (EXPERIMENTAL)"
+ tristate "RAID 1/4/5/6 target (EXPERIMENTAL)"
depends on BLK_DEV_DM && EXPERIMENTAL
+ select MD_RAID1
select MD_RAID456
select BLK_DEV_MD
---help---
- A dm target that supports RAID4, RAID5 and RAID6 mappings
+ A dm target that supports RAID1, RAID4, RAID5 and RAID6 mappings
A RAID-5 set of N drives with a capacity of C MB per drive provides
the capacity of C * (N - 1) MB, and protects against a failure