metadetach

Maintenance Commands metattach(1M)

NAME
metattach, metadetach - attach or detach metadevice to or
from a mirror or trans device, or attach space (blocks) to a
soft partition to grow the soft partition

SYNOPSIS
/usr/sbin/metattach [ -h ]

/usr/sbin/metattach [ -s setname ] mirror [ metadevice ]

/usr/sbin/metattach [ -s setname ] [ -i size ]
concat/stripe component...

/usr/sbin/metattach [ -s setname ] RAID component...

/usr/sbin/metattach [ -s setname ] softpart size

/usr/sbin/metattach [ -s setname ] trans log

/usr/sbin/metadetach [ -s setname ] [ -f ] mirror submir-
ror

/usr/sbin/metadetach [ -s setname ] [ -f ] trans

metattach is used to add submirrors to a mirror, add logging
devices to trans devices, grow metadevices, or grow soft
partitions. Growing metadevices can be done without inter-
rupting service. To grow the size of a mirror or trans, the
slices must be added to the submirrors or to the master dev-
ices.

Solstice DiskSuite 4.2.1 supports one-to-four-way mirrors.
Thus, you can only attach a metadevice to a mirror if there
are three or fewer submirrors beneath the mirror. Once a new
metadevice is attached to a mirror, metattach will automati-
cally start a resync operation to the new submirror.

Attaching a new logging device to a busy trans metadevice is
allowed, although a trans metadevice will start using its
new logging device only after the trans is idle (after it is
unmounted, for example). The busy trans will be in an
Attaching state (metastat) until the logging device is actu-
ally attached. Attaching a logging device in the Hard Error
or Error state (metastat) is not allowed.

metadetach is used to detach submirrors from mirrors, or
detach logging devices from trans metadevices.

When a submirror is detached from a mirror, it is no longer
part of the mirror, thus reads and writes to and from that
metadevice via the mirror are no longer performed through
the mirror. Detaching the only existing submirror is not
allowed. Detaching a submirror that has slices reported as
needing maintenance (by metastat) is not allowed unless the
-f (force) flag is used.

metadetach also detaches the logging device from a trans.
Once detached, the logging device is no longer part of the
trans, thus the trans is no longer logging and all benefits
of logging are lost. Any information on the logging device
that pertains to the master device is written to the master
device before the logging device is detached.

Detaching the logging device from a busy trans device is not
allowed unless the -f (force) flag is used. Even so, the
logging device is not actually detached until the trans is
idle. The trans is in the Detaching state (metastat) until
the logging device is detached.

Root privileges are required for all of the following
options except -h.

-f Force the detaching of metadevices that have com-
ponents that need maintenance or are busy. You can use
this option only when a mirror is in a maintenance
state that can be fixed with metareplace(1M). If the
mirror is in a maintenance state that can only be
fixed with metasync(1M) (as shown by the output of
metastat(1M)), metadetach -f will have no effect,
because the mirrors must be resynchronized before one
of them can be detached.

-h Displays a usage message.

-i size
Specifies the interlace value for stripes, where size
is a specified value followed by either `k' for kilo-
bytes, `m' for megabytes, or `b' for blocks. The units
can be either uppercase or lowercase. If size is not
specified, the size defaults to the interlace size of
the last stripe of the metadevice. When an interlace
size change is made on a stripe, it will be carried
forward on all stripes that follow.

-s setname
Specifies the name of the diskset on which the metat-
tach command or the metadetach command will work.
Using the -s option will cause the command to perform
its administrative function within the specified
diskset. Without this option, the command will perform
its function on local metadevices.

component...
The logical name for the physical slice (partition) on
a disk drive, such as /dev/dsk/c0t0d0s2, being added
to the concatenation, stripe, concatenation of
stripes, or RAID5 metadevice.

concat/stripe
Specifies the metadevice name of the concatenation,
stripe, or concatenation of stripes.

log Specifies the metadevice name of the logging device to
be attached to the trans metadevice.

metadevice
Specifies the name of the metadevice to be attached to
the mirror as a submirror. This metadevice must have
been previously created by the metainit command.

mirror
Specifies the mirror.

RAID Specifies the metadevice name of the RAID5 metadevice.

size Specifies the amount of space to add to the soft par-
tition in K or k for kilobytes, M or m for megabytes,
G or g for gigabytes, T or t for terabytes, and B or b
for blocks (sectors).

softpart
Specifies the metadevice name of the existing soft
partition.

submirror
The metadevice name of the submirror to be detached
from the mirror.

trans Specifies the metadevice name of the trans metadevice
(not the master or logging device).

Example 1: Concatenating a New Slice to a Metadevice

This example concatenates a single new slice to an existing
metadevice, d8. Afterwards, you would use the growfs(1M)
command to expand the file system.

# metattach d8 /dev/dsk/c0t1d0s2

Example 2: Detaching Logging Device from Trans Metadevice

This example detaches the logging device from a trans meta-
device d9. Notice that you do not have to specify the log-
ging device itself, as there can only be one.

# metadetach d9

Example 3: Expanding a RAID5 Metadevice

This example expands a RAID5 metadevice, d45, by attaching
another slice.

# metattach d45 /dev/dsk/c3t0d0s2

When you add additional slices to a RAID5 metadevice, the
additional space is devoted to data. No new parity blocks
are allocated. The data on the added slices is, however,
included in the overall parity calculations, so it is pro-
tected against single-device failure.

Example 4: Expanding a Soft Partition

The following example expands a soft partition, d42, by
attaching 150 Mbytes.

# metattach d42 150M

When you add additional space to a soft partition, the addi-
tional space is taken from any available space on the device
and might not be contiguous with the existing soft parti-
tion.

Example 5: Adding Space to Two-Way Mirror

This example adds space to a two-way mirror by adding a
slice to each submirror. Afterwards, you would use the
growfs(1M) command to expand the file system.

# metattach d9 /dev/dsk/c0t2d0s5
# metattach d10 /dev/dsk/c0t3d0s5

Example 6: Detaching a Submirror from a Mirror

This example detaches a submirror, d2, from a mirror, d4.

# metadetach d4 d2

Example 7: Adding Four Slices to Metadevice

This example adds four slices to an existing metadevice, d9.
Afterwards, you would use the growfs(1M) command to expand
the file system.

# metattach d9 /dev/dsk/c0t1d0s2 /dev/dsk/c0t2d0s2 /dev/dsk/c0t3d0s2 /dev/dsk/c0t4d0s2

The following exit values are returned:

0 Successful completion.

>0 An error occurred.

See attributes(5) for descriptions of the following attri-
butes:

tab() allbox; cw(2.750000i)| cw(2.750000i) lw(2.750000i)|
lw(2.750000i). ATTRIBUTE TYPEATTRIBUTE VALUE
AvailabilitySUNWmdu

metaclear(1M), metadb(1M), metadetach(1M), metahs(1M),
metainit(1M), metaoffline(1M), metaonline(1M),
metaparam(1M), metarecover(1M), metareplace(1M),
metaroot(1M), metaset(1M), metastat(1M), metasync(1M),
md.tab(4), md.cf(4), mddb.cf(4), attributes(5)

Solstice DiskSuite 4.2.1 Reference Manual

WARNING
When a submirror is detached from its mirror, the data on
the metadevice may not be the same as the data that existed
on the mirror prior to running metadetach. In particular, if
the -f option was needed, the metadevice and mirror probably
do not contain the same data.

SunOS 5.8 Last change: 11 May 2001 5