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Diffstat (limited to 'share/man/man4/raid.4')
| -rw-r--r-- | share/man/man4/raid.4 | 46 |
1 files changed, 29 insertions, 17 deletions
diff --git a/share/man/man4/raid.4 b/share/man/man4/raid.4 index 79d32165afc..4a00e638d7b 100644 --- a/share/man/man4/raid.4 +++ b/share/man/man4/raid.4 @@ -1,5 +1,5 @@ -.\" $OpenBSD: raid.4,v 1.8 1999/09/23 04:12:04 alex Exp $ -.\" $NetBSD: raid.4,v 1.5 1999/03/16 01:19:17 garbled Exp $ +.\" $OpenBSD: raid.4,v 1.9 2000/01/07 14:52:28 peter Exp $ +.\" $NetBSD: raid.4,v 1.8 1999/12/15 22:07:33 abs Exp $ .\" .\" .\" Copyright (c) 1998 The NetBSD Foundation, Inc. @@ -174,21 +174,32 @@ RAID levels may be combined in a hierarchical fashion. For example, a RAID 0 device can be constructed out of a number of RAID 5 devices (which, in turn, may be constructed out of the physical disks, or of other RAID devices). .Pp -At the time of this writing, it is -.Em imperative -that drives be -.Sq nailed down -at their respective addresses (i.e. not left free-floating, where a -drive with SCSI ID of 4 can end up as /dev/sd0c). Consider a system -with three SCSI drives at SCSI IDs 4, 5, and 6, and which map to -components /dev/sd0e, /dev/sd1e, and /dev/sd2e. If the drive with -SCSI ID 5 fails, -and the system reboots, the old /dev/sd2e will show up as /dev/sd1e. -If the RAID driver is automatically configured, it will only detect -that /dev/sd2e has failed, and will not notice that /dev/sd2e has -actually become /dev/sd1e. Hopefully this will change within a few -days of this writing with the addition of MD5 checksums to each of the -components. +It is important that drives be hard-coded at their respective +addresses (i.e. not left free-floating, where a drive with SCSI ID of +4 can end up as /dev/sd0c) for well-behaved functioning of the RAID +device. For normal SCSI drives, for example, the following can be +used to fix the device addresses: +.Bd -unfilled -offset indent +sd0 at scsibus0 target 0 lun ? # SCSI disk drives +sd1 at scsibus0 target 1 lun ? # SCSI disk drives +sd2 at scsibus0 target 2 lun ? # SCSI disk drives +sd3 at scsibus0 target 3 lun ? # SCSI disk drives +sd4 at scsibus0 target 4 lun ? # SCSI disk drives +sd5 at scsibus0 target 5 lun ? # SCSI disk drives +sd6 at scsibus0 target 6 lun ? # SCSI disk drives +.Ed +.Pp +See +.Xr sd 4 +for more information. The rationale for fixing the device addresses +is as follows: Consider a system with three SCSI drives at SCSI ID's +4, 5, and 6, and which map to components /dev/sd0e, /dev/sd1e, and +/dev/sd2e of a RAID 5 set. If the drive with SCSI ID 5 fails, and the +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. .Pp The first step to using the .Nm @@ -264,6 +275,7 @@ device special files. .Xr fsck 8 , .Xr mount 8 , .Xr newfs 8 , +.Xr sd 4 , .Xr raidctl 8 .Sh HISTORY The |