'\" te
.\" Copyright (c) 2003, Sun Microsystems, Inc.  All Rights Reserved
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
.TH md 7D "29 Aug 2003" "SunOS 5.11" "Devices"
.SH NAME
md \- user configurable pseudo device driver
.SH DESCRIPTION
.sp
.LP
\fBmd\fR is a user configurable pseudo device driver that provides disk
concatenation, striping, mirroring, RAID5 metadevices, trans metadevices, and
hot spare utilities. Trans devices are no longer supported and have been
replaced by UFS logging. See \fBmount_ufs\fR(1M).
.sp
.LP
The block devices access the disk using the system's normal buffering mechanism
and are read and written without regard to physical disk records. There is also
a ``raw'' device which provides for direct transmission between the disk and
the user's read or write buffer. A single read or write call usually results in
one I/O operation; raw I/O is therefore considerably more efficient when many
bytes are transmitted. The names of the block devices are found in
\fB/dev/md/dsk\fR; the names of the raw devices are found in
\fB/dev/md/rdsk\fR. Metadevices have the appearance of whole disks; there are
no slices (partitions).
.sp
.LP
I/O requests (such as \fBlseek\fR(2)) to the metadevices must have an offset
that is a multiple of 512 bytes (DEV_BSIZE), or the driver returns an EINVAL
error. If the transfer length is not a multiple of 512 bytes, the tranfer count
is rounded up by the driver.
.sp
.LP
The \fBmd\fR pseudo device drivers support all disk devices on all Solaris 2.4
or later Solaris systems.
.SH IOCTLS
.sp
.LP
This section provides a list of the ioctls supported by the metadisk driver.
.sp
.LP
The following ioctls are valid when issued to the raw metadevice, such as
\fB/dev/md/rdsk/d0\fR. See \fBdkio\fR(7I) for additional information.
.sp
.ne 2
.mk
.na
\fB\fBDKIOCGGEOM\fR\fR
.ad
.RS 14n
.rt  
This ioctl is used to get the disk geometry. The metadisk driver fills in the
\fBdkg_nhead\fR, \fBdkg_nsect\fR, \fBdkg_rpm\fR, \fBdkg_write_reinstruct\fR and
\fBdkg_read_reinstruct\fR from the first component of the metadevice (at
\fBmetainit\fR time). \fBdkg_ncyl\fR is calculated using the size of the
metadevice (reported by \fBmetastat\fR) divided by (dkg_nhead * dkg_nsect). The
total size is always a multiple of (dkg_nhead * dkg_nsect). If the first
component of a metadevice \fIdoes not\fR start on cylinder number 0, then the
dkg_ncyl is increased by one cylinder; because DKIOCGVTOC reports the
metadevice as starting on cylinder 1. The side effect here is that it looks
like cylinder 0 is not being used, but all the arithmetic works out correctly.
If the metadevice is not set up, then ENXIO is returned.
.RE

.sp
.ne 2
.mk
.na
\fB\fBDKIOCINFO\fR\fR
.ad
.RS 14n
.rt  
When issued to the administrative device or metadevice, this ioctl sets
\fBdki_unit\fR to the unit number of the metadevice, \fBdki_ctype\fR to a value
of DKC_MD, and \fBdki_partition\fR to 0, because there are no slices.
.RE

.sp
.ne 2
.mk
.na
\fB\fBDKIOCGVTOC\fR\fR
.ad
.RS 14n
.rt  
This ioctl returns the current vtoc. If one has not been written, then a
default vtoc is returned. \fBv_nparts\fR is always 1. \fBv_part[0].p_start\fR
is 0 if the first component of the metadevice starts on cylinder 0. Otherwise,
the \fBp_start\fR field is the starting sector of cylinder 1.
\fBv_part[0].p_size\fR is the same as the total size reported by
\fBmetastat\fR.
.RE

.sp
.ne 2
.mk
.na
\fB\fBDKIOCSVTOC\fR\fR
.ad
.RS 14n
.rt  
This ioctl stores the vtoc in the metadevice state database so it is persistent
across reboots.
.RE

.SH DIAGNOSTICS
.SS "Notice Log Messages"
.sp
.LP
The informative log messages include:
.sp
.in +2
.nf
md: d\fInum\fR: Hotspared device \fIdev\fR with \fIdev\fR
.fi
.in -2

.sp
.LP
The first device name listed has been hot spare replaced with the second device
name listed.
.sp
.in +2
.nf
md: d\fInum\fR: Hotspared device dev(\fInum\fR,\fInum\fR) with dev(\fInum\fR,\fInum\fR)
.fi
.in -2

.sp
.LP
The first device number listed has been hot spare replaced with the second
device number listed.
.sp
.in +2
.nf
md: Could not load misc /\fIdev\fR
.fi
.in -2

.sp
.LP
The named \fBmisc\fR module is not loadable. It is possibly missing, or
something else has been copied over it.
.sp
.in +2
.nf
md: d\fInum\fR: no mem for property \fIdev\fR
.fi
.in -2

.sp
.LP
Memory could not be allocated in the \fBprop_op\fR entry point.
.sp
.in +2
.nf
md: db: Parsing error on '\fIdev\fR' 
  
.fi
.in -2
.sp

.sp
.LP
Set command in \fB/kernel/drv/md.conf\fR for the \fBmddb.bootlist\fR
\fI<number>\fR is not in the correct format. \fBmetadb\fR \fB-p\fR can be run
to put the correct set commands into the \fB/kernel/drv/md.conf\fR file.
.sp
.in +2
.nf
md: d\fInum\fR: \fIdev\fR(\fInum\fR,\fInum\fR) needs maintenance 
md: d\fInum\fR: \fIdev\fR needs maintenance
.fi
.in -2

.sp
.LP
An I/O or open error has occurred on a device within a mirror causing a
component in the mirror to change to the Maintenance state.
.sp
.LP
\fBmd: d\fR\fInum\fR\fB: \fR\fIdev\fR\fB(\fR\fInum\fR\fB,\fR\fInum\fR\fB) last
erred\fR \fBmd: d\fR\fInum\fR\fB: \fR\fIdev\fR\fB last erred\fR
.sp
.LP
An I/O or open error has occurred on a device within a mirror and the data is
not replicated elsewhere in the mirror. This is causing the component in the
mirror to change to the Last Erred state.
.SS "Warning Log Messages"
.sp
.LP
The warning log messages include:
.sp
.in +2
.nf
md: State database is stale
.fi
.in -2

.sp
.LP
This error message comes when there are not enough usable replicas for the
state database to be able to update records in the database. All accesses to
the metadevice driver will fail. To fix this problem, more replicas need to be
added or inaccessible replicas need to be deleted.
.sp
.in +2
.nf
md: d\fInum\fR: read error on \fIdev\fRmd: d\fInum\fR: write error on \fIdev\fR
.fi
.in -2

.sp
.LP
A read or write error has occurred on the specified submirror, at the specified
device name. This happens if any read or write errors occur on a submirror.
.sp
.in +2
.nf
md: d\fInum\fR: read error on dev(\fInum\fR,\fInum\fR)md: d\fInum\fR: write error on dev(
\fInum\fR,\fInum\fR)
.fi
.in -2

.sp
.LP
A read or write error has occurred on the specified submirror, at the specified
device number. This happens if any read or write errors occur on a submirror.
.sp
.in +2
.nf
md: State database commit failed
md: State database delete failed
.fi
.in -2

.sp
.LP
These messages occur when there have been device errors on components where the
state database replicas reside. These errors only occur when more than half of
the replicas have had device errors returned to them. For instance, if you have
three components with state database replicas and two of the components report
errors, then these errors may occur. The state database commit or delete is
retried periodically. If a replica is added, then the commit or delete will
finish and the system will be operational. Otherwise the system will timeout
and panic.
.sp
.in +2
.nf
md: d\fInum\fR: Cannot load \fIdev\fR driver
.fi
.in -2
.sp

.sp
.LP
Underlying named driver module is not loadable (for example, \fBsd\fR,
\fBid\fR, \fBxy\fR, or a third-party driver). This could indicate that the
driver module has been removed.
.sp
.in +2
.nf
md: Open error of hotspare \fIdev\fRmd: Open error of hotspare dev(\fInum\fR,\fInum\fR)
.fi
.in -2

.sp
.LP
Named hotspare is not openable, or underlying driver is not loadable.
.SS "Panic Log Messages"
.sp
.LP
The panic log messages include:
.sp
.in +2
.nf
md: d\fInum\fR: Unknown close typemd: d\fInum\fR: Unknown open type
.fi
.in -2

.sp
.LP
Metadevice is being opened/closed with an unknown open type (OTYP).
.sp
.in +2
.nf
md: State database problem
.fi
.in -2

.sp
.LP
Failed metadevice state database commit or delete has been retried the default
100 times.
.SH FILES
.sp
.ne 2
.mk
.na
\fB\fB/dev/md/dsk/\fR\fBd\fIn\fR\fR \fR
.ad
.RS 30n
.rt  
block device (where \fIn\fR is the device number)
.RE

.sp
.ne 2
.mk
.na
\fB\fB/dev/md/rdsk/\fR\fBd\fIn\fR\fR \fR
.ad
.RS 30n
.rt  
raw device (where \fIn\fR is the device number)
.RE

.sp
.ne 2
.mk
.na
\fB\fB/dev/md/\fIsetname\fR/dsk/\fR\fBd\fIn\fR\fR \fR
.ad
.RS 30n
.rt  
block device (where \fIsetname\fR is the name of the diskset and \fIn\fR is the
device number)
.RE

.sp
.ne 2
.mk
.na
\fB\fB/dev/md/\fIsetname\fR/rdsk/\fR\fBd\fIn\fR\fR \fR
.ad
.RS 30n
.rt  
raw device (where \fIsetname\fR is the name of the diskset and \fIn\fR is the
device number)
.RE

.sp
.ne 2
.mk
.na
\fB\fB/dev/md/admin\fR \fR
.ad
.RS 30n
.rt  
administrative device
.RE

.sp
.ne 2
.mk
.na
\fB\fB/kernel/drv/md\fR \fR
.ad
.RS 30n
.rt  
driver module
.RE

.sp
.ne 2
.mk
.na
\fB\fB/kernel/drv/md.conf\fR \fR
.ad
.RS 30n
.rt  
driver configuration file
.RE

.sp
.ne 2
.mk
.na
\fB\fB/kernel/misc/md_stripe\fR \fR
.ad
.RS 30n
.rt  
stripe driver misc module
.RE

.sp
.ne 2
.mk
.na
\fB\fB/kernel/misc/md_mirror\fR \fR
.ad
.RS 30n
.rt  
mirror driver misc module
.RE

.sp
.ne 2
.mk
.na
\fB\fB/kernel/misc/md_hotspares\fR \fR
.ad
.RS 30n
.rt  
hotspares driver misc module
.RE

.sp
.ne 2
.mk
.na
\fB\fB/kernel/misc/md_trans\fR \fR
.ad
.RS 30n
.rt  
metatrans driver for UFS logging
.RE

.sp
.ne 2
.mk
.na
\fB\fB/kernel/misc/md_raid\fR \fR
.ad
.RS 30n
.rt  
RAID5 driver misc module
.RE

.SH SEE ALSO
.sp
.LP
\fBmdmonitord\fR(1M), \fBmetaclear\fR(1M), \fBmetadb\fR(1M),
\fBmetadetach\fR(1M), \fBmetahs\fR(1M), \fBmetainit\fR(1M),
\fBmetaoffline\fR(1M), \fBmetaonline\fR(1M), \fBmetaparam\fR(1M),
\fBmetarecover\fR(1M), \fBmetarename\fR(1M), \fBmetareplace\fR(1M),
\fBmetaroot\fR(1M), \fBmetassist\fR(1M), \fBmetaset\fR(1M), \fBmetastat\fR(1M),
\fBmetasync\fR(1M), \fBmetattach\fR(1M), \fBmd.cf\fR(4), \fBmd.tab\fR(4),
\fBattributes\fR(5),
.sp
.LP
\fISolaris Volume Manager Administration Guide\fR
.SH NOTES
.sp
.LP
Trans metadevices have been replaced by UFS logging. Existing trans devices are
\fBnot\fR logging--they pass data directly through to the underlying device.
See \fBmount_ufs\fR(1M) for more information about UFS logging.