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Note auto-detection and auto-configuration, as well as the ability to

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auto-configure even if the components are rearranged.
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oster 2000-02-26 01:14:16 +00:00
parent 0b97eb1052
commit a4d828bd4e
1 changed files with 33 additions and 9 deletions
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42
share/man/man4/raid.4
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@ -1,4 +1,4 @@
.\" $NetBSD: raid.4,v 1.10 2000/01/23 02:04:10 oster Exp $
.\" $NetBSD: raid.4,v 1.11 2000/02/26 01:14:16 oster Exp $
.\"
.\" Copyright (c) 1998 The NetBSD Foundation, Inc.
.\" All rights reserved.
@ -112,8 +112,8 @@ The RAID driver supports and enforces the use of
A
.Sq component label
contains important information about the component, including a
user-specified serial number, the row and column of that component in the RAID
set, and whether the data (and parity) on the component is
user-specified serial number, the row and column of that component in
the RAID set, and whether the data (and parity) on the component is
.Sq clean .
If the driver determines that the labels are very inconsistent with
respect to each other (e.g. two or more serial numbers do not match)
@ -130,6 +130,17 @@ and the RAID set will begin operation in degraded mode.
If all of the components are consistent among themselves, the RAID set
will configure normally.
.Pp
Component labels are also used to support the auto-detection and
auto-configuration of RAID sets. A RAID set can be flagged as
auto-configurable, in which case it will be configured automatically
during the kernel boot process. RAID filesystems which are
automatically configured are also eligible to be the root filesystem.
While there is no support for booting directly from a RAID set, it is
possible to boot from a small partition which contains a kernel, and
have the root filesystem on a RAID set. See
.Xr raidctl 8
for more information on auto-configuration of RAID sets.
.Pp
The driver supports
.Sq hot spares ,
disks which are on-line, but are not
@ -151,17 +162,23 @@ The user-land utility for doing all
configuration and other operations
is
.Xr raidctl 8 .
For any of the RAID flavours which have parity data,
Most importantly,
.Xr raidctl 8
must be used with the
.Fl i
option to re-write the data when either a) a new RAID device is
option to initialize all RAID sets. In particular, this
initialization includes re-building the parity data. This rebuilding
of parity data is also required when either a) a new RAID device is
brought up for the first time or b) after an un-clean shutdown of a
RAID device. By performing this on-demand recomputation of all parity
RAID device. By using the
.Fl P
option to
.Xr raidctl 8 ,
and performing this on-demand recomputation of all parity
before doing a
.Xr fsck 8
or a
.Xr newfs 8
.Xr newfs 8 ,
filesystem integrity and parity integrity can be ensured. It bears
repeating again that parity recomputation is
.Ar required
@ -197,7 +214,11 @@ system reboots, the old /dev/sd2e will show up as /dev/sd1e. The RAID
driver is able to detect that component positions have changed, and
will not allow normal configuration. If the device addresses are hard
coded, however, the RAID driver would detect that the middle component
is unavailable, and bring the RAID 5 set up in degraded mode.
is unavailable, and bring the RAID 5 set up in degraded mode. Note
that the auto-detection and auto-configuration code does not care
about where the components live. The auto-configuration code will
correctly configure a device even after any number of the components
have been re-arranged.
.Pp
The first step to using the
.Nm
@ -225,7 +246,10 @@ disklabel for the
device.
As well, all component partitions must be of the type
.Dv FS_BSDFFS
(e.g. 4.2BSD).
(e.g. 4.2BSD) or
.Dv FS_RAID .
The use of the latter is strongly encouraged, and is required if
auto-configuration of the RAID set is desired.
.Pp
A more detailed treatment of actually using a
.Nm