man pages section 1M: System Administration Commands

metadetach(1M)

Name

metattach, metadetach– attach or detach a metadevice

Synopsis

/usr/sbin/metattach [-h]

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

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

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

/usr/sbin/metattach [-s setname] [-A alignment] softpart
 size | all

/usr/sbin/metadetach [-s setname] [-f] mirror submirror

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

Description

metattach adds submirrors to a mirror, grows metadevices, or grows soft partitions. Growing metadevices can be done without interrupting service. To grow the size of a mirror or trans, the slices must be added to the submirrors or to the master devices.

Solaris Volume Manager supports storage devices and logical volumes greater than 1 terabyte (TB) when a system runs a 64-bit Solaris kernel. Support for large volumes is automatic. If a device greater than 1 TB is created, Solaris Volume Manager configures it appropriately and without user intervention.

If a system with large volumes is rebooted under a 32–bit Solaris kernel, the large volumes are visible through metastat output. Large volumes cannot be accessed, modified or deleted, and no new large volumes can be created. Any volumes or file systems on a large volume in this situation are also unavailable. If a system with large volumes is rebooted under a version of Solaris prior to the Solaris 9 4/03 release, Solaris Volume Manager does not start. You must remove all large volumes before Solaris Volume Manager runs under an earlier version of the Solaris Operating System.

Solaris Volume Manager supports one-to-four-way mirrors. 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 automatically starts a resync operation to the new submirror.

metadetach detaches submirrors from mirrors and 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 by way of 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. This step is necessary before you can clear the trans volume. Trans metadevices have been replaced by UFS logging. Existing trans devices are not logging. They pass data directly through to the underlying device. See mount_ufs(1M) for more information about UFS logging.

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.

Options

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

The following options are supported:

-A alignment

Set the value of the soft partition extent alignment. Use this option when it is important specify a starting offset for the soft partition. It preserves the data alignment between the metadevice address space and the address space of the underlying physical device.

For example, a hardware device that does checksumming should not have its I/O requests divided by Solaris Volume Manager. In this case, use a value from the hardware configuration as the value for the alignment. When using this option in conjunction with a software I/O load, the alignment value corresponds to the I/O load of the application. This prevents I/O from being divided unnecessarily and affecting performance.

-f

Force the detaching of metadevices that have components 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 has no effect, because the mirrors must be resynchronized before one of them can be detached.

-h

Display a usage message.

-i interlace

Specify the interlace value for stripes, where size is a specified value followed by either k for kilobytes, 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 is carried forward on all stripes that follow.

-s setname

Specify the name of the diskset on which the metattach command or the metadetach command works.. Using the -s option causes the command to perform its administrative function within the specified diskset. Without this option, the command performs its function on local metadevices.

Operands

The following operands are supported:

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: The metadevice name of the concatenation, stripe, or concatenation of stripes.
log: The metadevice name of the logging device to be attached to the trans metadevice.
metadevice: The metadevice name to be attached to the mirror as a submirror. This metadevice must have been previously created by the metainit command.
mirror: The name of the mirror.
RAID: The metadevice name of the RAID5 metadevice.
size | all: The amount of space to add to the soft partition 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). All values represent powers of 2, and upper and lower case options are equivalent. Only integer values are permitted. The literal all specifies that the soft partition should grow to occupy all available space on the underlying volume.
softpart: The metadevice name of the existing soft partition.
submirror: The metadevice name of the submirror to be detached from the mirror.
trans: The metadevice name of the trans metadevice (not the master or logging device).

Examples

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 metadevice d9. Notice that you do not have to specify the logging 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 protected against single-device failure.

Example 4 Expanding a Soft Partition

The following example expands a soft partition, d42, attaching all space available on the underlying device.

# metattach d42 all

When you add additional space to a soft partition, the additional space is taken from any available space on the slice and might not be contiguous with the existing soft partition.

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

This example tells the mirror to grow to the size of the underlying devices

# metattach d11

This example increases the size of the UFS on the device so the space can be used.

# growfs -M /export /dev/md/dsk/d11

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

Example 8 Setting the Value of the Soft Partition Extent Alignment

This example shows how to set the alignment of the soft partition to 1mb when the soft partition is expanded.

# metattach -s red -A 2m d13 1m

Exit Status

The following exit values are returned:

0: Successful completion.
>0: An error occurred.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Availability	SUNWmdu

Warnings

This section provides information regarding warnings for devices greater than 1 TB and for multi-way mirrors.

Devices and Volumes Greater Than 1 TB

Do not create large (>1 TB) volumes if you expect to run the Solaris Operating System with a 32-bit kernel or if you expect to use a version of the Solaris Operating System prior to Solaris 9 4/03.

Multi-Way Mirrors

When a submirror is detached from its mirror, the data on the metadevice might 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.

Notes

Trans metadevices have been replaced by UFS logging. Existing trans devices are not logging. They pass data directly through to the underlying device. See mount_ufs(1M) for more information about UFS logging.

SunOS 5.10 Last Revised 8 Feb 2007