dm: raid456 basic support

[mv-sheeva.git] / drivers / md / Kconfig

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index bf1a95e315592bf2cb5f1234960e7d66fa625ced..98d9ec85e0eb1723a04b2218563a803213b52cd6 100644 (file)
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -240,6 +240,30 @@ config DM_MIRROR
          Allow volume managers to mirror logical volumes, also
          needed for live data migration tools such as 'pvmove'.
 
+config DM_RAID
+       tristate "RAID 4/5/6 target (EXPERIMENTAL)"
+       depends on BLK_DEV_DM && EXPERIMENTAL
+       select MD_RAID456
+       select BLK_DEV_MD
+       ---help---
+        A dm target that supports 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
+        of a single drive. For a given sector (row) number, (N - 1) drives
+        contain data sectors, and one drive contains the parity protection.
+        For a RAID-4 set, the parity blocks are present on a single drive,
+        while a RAID-5 set distributes the parity across the drives in one
+        of the available parity distribution methods.
+
+        A RAID-6 set of N drives with a capacity of C MB per drive
+        provides the capacity of C * (N - 2) MB, and protects
+        against a failure of any two drives. For a given sector
+        (row) number, (N - 2) drives contain data sectors, and two
+        drives contains two independent redundancy syndromes.  Like
+        RAID-5, RAID-6 distributes the syndromes across the drives
+        in one of the available parity distribution methods.
+
 config DM_LOG_USERSPACE
        tristate "Mirror userspace logging (EXPERIMENTAL)"
        depends on DM_MIRROR && EXPERIMENTAL && NET