is not a Software RAID mechanism, but does involve
multiple devices:
each device is a path to one common physical storage device.
+New installations should not use md/multipath as it is not well
+supported and has no ongoing development. Use the Device Mapper based
+multipath-tools instead.
.B FAULTY
is also not true RAID, and it only involves one device. It
is a collection of devices that are
managed as a set. This is similar to the set of devices connected to
a hardware RAID controller. The set of devices may contain a number
-of different RAID arrays each utilising some (or all) blocks from a
+of different RAID arrays each utilising some (or all) of the blocks from a
number of the devices in the set. For example, two devices in a 5-device set
-might form a RAID1 used the whole devices. The remaining three might
+might form a RAID1 using the whole devices. The remaining three might
have a RAID5 over the first half of each device, and a RAID0 over the
second half.
.I mdadm
creates a
.B CONTAINER
-device, it just represents the metadata. Other normal arrays (RAID1
-etc) can be created inside that container.
-
-
-.\".I mdadm
-.\"is a program that can be used to create, manage, and monitor
-.\"MD devices. As
-.\"such it provides a similar set of functionality to the
-.\".B raidtools
-.\"packages.
-.\"The key differences between
-.\".I mdadm
-.\"and
-.\".B raidtools
-.\"are:
-.\".IP \(bu 4
-.\".I mdadm
-.\"is a single program and not a collection of programs.
-.\".IP \(bu 4
-.\".I mdadm
-.\"can perform (almost) all of its functions without having a
-.\"configuration file and does not use one by default. Also
-.\".I mdadm
-.\"helps with management of the configuration
-.\"file.
-.\".IP \(bu 4
-.\".I mdadm
-.\"can provide information about your arrays (through Query, Detail, and Examine)
-.\"that
-.\".B raidtools
-.\"cannot.
-.\".P
-.\".I mdadm
-.\"does not use
-.\".IR /etc/raidtab ,
-.\"the
-.\".B raidtools
-.\"configuration file, at all. It has a different configuration file
-.\"with a different format and a different purpose.
+device, the device just represents the metadata. Other normal arrays (RAID1
+etc) can be created inside the container.
.SH MODES
mdadm has several major modes of operation:
system. As each device is detected,
.I mdadm
has a chance to include it in some array as appropriate.
-.P
+
If a
.B CONTAINER
is passed to
for the given homehost will be reported as such.
When using Auto-Assemble, only arrays tagged for the given homehost
-will be assembled.
+will be allowed to use 'local' names (i.e. not ending in '_' followed
+by a digit string).
.SH For create, build, or grow:
will not try to be so clever.
.TP
-.BR \-a ", " "\-\-auto{=no,yes,md,mdp,part,p}{NN}"
-Instruct mdadm to create the device file if needed, possibly allocating
+.BR \-a ", " "\-\-auto{=yes,md,mdp,part,p}{NN}"
+Instruct mdadm how to create the device file if needed, possibly allocating
an unused minor number. "md" causes a non-partitionable array
-to be used. "mdp", "part" or "p" causes a partitionable array (2.6 and
+to be used (though since Linux 2.6.28, these array devices are in fact
+partitionable). "mdp", "part" or "p" causes a partitionable array (2.6 and
later) to be used. "yes" requires the named md device to have
a 'standard' format, and the type and minor number will be determined
-from this. See DEVICE NAMES below.
+from this. With mdadm 3.0, device creation is normally left up to
+.I udev
+so this option is unlikely to be needed.
+See DEVICE NAMES below.
The argument can also come immediately after
"\-a". e.g. "\-ap".
projects / thirdparty / mdadm.git / blobdiff