DISKLAYOUT(1m)DISKLAYOUT(1m)NAMEdisklayout-- Lay out a ZFS pool configuration from a disk inventory
SYNOPSISdisklayout [-f file] [layout]
DESCRIPTIONdisklayout generates a JSON description of a ZFS pool configuration
suitable for use by the mkzpool(1M) utility. The utility may be run in
two modes; when the -f option is given, the specified file is taken to
be the output of the diskinfo(1M) command and used as the source of
information about the available disks. Otherwise, the disks currently
present on the system will be enumerated and the utility will attempt
to generate a pool layout that uses as many of the available disks as
possible. The generated layout will not contain any removable disks.
The utility does not create any pools, nor does it alter the contents
of the disks. The generated JSON is written to standard output. Its
format is described in detail in OUTPUT FIELDS below.
Unless the -f option is given, diskinfo must be used in the global zone
only so that it can enumerate the host´s available disks.
DEVICE ASSIGNMENT
Devices will be assigned to one of three basic roles: primary storage,
dedicated intent log ("log"), or second-level ARC (or "cache").
Devices that are not known to be solid-state will not be assigned the
log or cache roles. The assignment of solid-state devices to the log
role will be made before any are assigned the cache role. Broadly, the
intent is to define a pool configuration that provides a good balance
of performance, durability, and usable capacity given the available
device inventory. If there are inadequate devices to do this, disklay‐
out will attempt to define a functional pool with redundancy. If there
is a single device, disklayout will define a pool with that single
device.
When at least 5 primary storage devices are available, disklayout
always allocates at least one spare. Additional spares may be allo‐
cated as the total number of primary storage devices increases and/or
if the number of available primary storage devices does not divide
evenly by the number of devices per vdev with enough left over to pro‐
vide the minimum number of spares.
When constructing RAIDZ-type layouts, disklayout will consider a range
of stripe widths (i.e., number of leaf devices per RAIDZ-n vdev). The
number of leaf devices per vdev will be at least 3 for RAIDZ, at least
5 for RAIDZ-2, and at least 7 for RAIDZ-3. Some versions of this util‐
ity may consider only stripes wider than the limits documented here.
This utility may not support all RAIDZ-n layouts.
Other than as described here, the heuristics used to select layouts and
to optimise allocation of devices are not an interface and are subject
to change at any time without notice.
OPTIONS-f file
Use file as the source of information about available disks. The run‐
ning system will not be interrogated; in this mode, the utility may be
used in a zone if desired.
layout
Specify the class of pool layout to generate. By default, disklayout
selects a pool layout class based on the type, number, and size of
available storage devices. If you specify a layout class, it will gen‐
erate a configuration of that class instead. If it is not possible to
do so given the available devices, an error will occur; see ERRORS
below. The set of supported layouts includes at least "single", "mir‐
ror", and "raidz2", and will be listed if you specify an unsupported
layout.
OUTPUT FIELDS
"spares"
An array of device specifications that are allocated as hot spares.
"vdevs"
An array of vdev specifications allocated to the active pool.
"capacity"
The number of bytes of usable storage in the pool. This is the amount
of user data that the pool can store, taking into account devices
reserved for spares and mirrored/parity devices.
"logs"
An array of device specifications that are allocated as dedicated
intent log devices. There is no internal structure; all log devices
are striped.
"cache"
An array of device specifications that are allocated as dedicated sec‐
ond-level ARC devices. There is no internal structure.
VDEV SPECIFICATIONS
A vdev specification contains the following properties:
"type"
The vdev type, as defined by ZFS. See zpool(1M).
"devices"
An array of device specifications allocated to the vdev.
DEVICE SPECIFICATIONS
Each device is specified by the following properties:
"name"
The base name of the device´s nodes under /dev/dsk.
"vid"
The vendor identification string of the device. See diskinfo(1M).
"pid"
The product identification string of the device. See diskinfo(1M).
"size"
The storage capacity in bytes of the device.
ERRORS
If the requested layout class cannot be satisfied by the available
devices, or if the set of available devices does not include any usable
primary storage devices, an error will occur. The resulting JSON out‐
put will contain the original device roster (in JSON format) and a text
description of the error. This message is not localised.
SEE ALSOdiskinfo(1M), mkzpool(1M), sd(7D), zpool(1M)
May 2014 DISKLAYOUT(1m)
