depends on BLK_DEV_MD && EXPERIMENTAL
---help---
RAID-10 provides a combination of striping (RAID-0) and
- mirroring (RAID-1) with easier configuration and more flexable
+ mirroring (RAID-1) with easier configuration and more flexible
layout.
Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
- be the same size (or atleast, only as much as the smallest device
+ be the same size (or at least, only as much as the smallest device
will be used).
RAID-10 provides a variety of layouts that provide different levels
of redundancy and performance.
ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
+ If unsure, say Y.
-config MD_RAID5
- tristate "RAID-4/RAID-5 mode"
+config MD_RAID456
+ tristate "RAID-4/RAID-5/RAID-6 mode"
depends on BLK_DEV_MD
---help---
A RAID-5 set of N drives with a capacity of C MB per drive provides
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.
+
Information about Software RAID on Linux is contained in the
Software-RAID mini-HOWTO, available from
<http://www.tldp.org/docs.html#howto>. There you will also
learn where to get the supporting user space utilities raidtools.
- If you want to use such a RAID-4/RAID-5 set, say Y. To compile
- this code as a module, choose M here: the module will be called raid5.
+ If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
+ compile this code as a module, choose M here: the module
+ will be called raid456.
If unsure, say Y.
-config MD_RAID6
- tristate "RAID-6 mode (EXPERIMENTAL)"
- depends on BLK_DEV_MD && EXPERIMENTAL
+config MD_RAID5_RESHAPE
+ bool "Support adding drives to a raid-5 array (experimental)"
+ depends on MD_RAID456 && EXPERIMENTAL
---help---
- WARNING: RAID-6 is currently highly experimental. If you
- use it, there is no guarantee whatsoever that it won't
- destroy your data, eat your disk drives, insult your mother,
- or re-appoint George W. Bush.
+ A RAID-5 set can be expanded by adding extra drives. This
+ requires "restriping" the array which means (almost) every
+ block must be written to a different place.
- 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.
-
- RAID-6 requires mdadm-1.5.0 or later, available at:
+ This option allows such restriping to be done while the array
+ is online. However it is still EXPERIMENTAL code. It should
+ work, but please be sure that you have backups.
- ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
+ You will need mdadm version 2.4.1 or later to use this
+ feature safely. During the early stage of reshape there is
+ a critical section where live data is being over-written. A
+ crash during this time needs extra care for recovery. The
+ newer mdadm takes a copy of the data in the critical section
+ and will restore it, if necessary, after a crash.
- If you want to use such a RAID-6 set, say Y. To compile
- this code as a module, choose M here: the module will be
- called raid6.
+ The mdadm usage is e.g.
+ mdadm --grow /dev/md1 --raid-disks=6
+ to grow '/dev/md1' to having 6 disks.
- If unsure, say N.
+ Note: The array can only be expanded, not contracted.
+ There should be enough spares already present to make the new
+ array workable.
config MD_MULTIPATH
tristate "Multipath I/O support"
tristate "Snapshot target (EXPERIMENTAL)"
depends on BLK_DEV_DM && EXPERIMENTAL
---help---
- Allow volume managers to take writeable snapshots of a device.
+ Allow volume managers to take writable snapshots of a device.
config DM_MIRROR
tristate "Mirror target (EXPERIMENTAL)"
A target that discards writes, and returns all zeroes for
reads. Useful in some recovery situations.
+config DM_MULTIPATH
+ tristate "Multipath target (EXPERIMENTAL)"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ Allow volume managers to support multipath hardware.
+
+config DM_MULTIPATH_EMC
+ tristate "EMC CX/AX multipath support (EXPERIMENTAL)"
+ depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ Multipath support for EMC CX/AX series hardware.
+
endmenu
git://git.onelab.eu / linux-2.6.git / blobdiff