vdev_id.conf5

Overview

vdev_id.conf is the configuration file for vdev_id(8). It controls the default behavior of vdev_id(8) while it is mapping a disk device name to an alias.

The vdev_id.conf file uses a simple format consisting of a keyword followed by one or more values on a single line. Any line not beginning with a recognized keyword is ignored. Comments may optionally begin with a hash character.

The following keywords and values are used.

alias name devlink

Maps a device link in the /dev directory hierarchy to a new device name. The udev rule defining the device link must have run prior to vdev_id(8). A defined alias takes precedence over a topology-derived name, but the two naming methods can otherwise coexist. For example, one might name drives in a JBOD with the sas_direct topology while naming an internal L2ARC device with an alias.

name is the name of the link to the device that will by created under /dev/disk/by-vdev.

devlink is the name of the device link that has already been defined by udev. This may be an absolute path or the base filename.

channel [pci_slot] port name

Maps a physical path to a channel name (typically representing a single disk enclosure).

enclosure_symlinks yes|no

Additionally create /dev/by-enclosure symlinks to the disk enclosure sg devices using the naming scheme from vdev_id.conf. enclosure_symlinks is only allowed for sas_direct mode.

enclosure_symlinks_prefix prefix

Specify the prefix for the enclosure symlinks in the form /dev/by-enclosure/⟨prefix⟩-⟨channel⟩⟨num⟩

Defaults to “enc”.

slot prefix new [channel]

Maps a disk slot number as reported by the operating system to an alternative slot number. If the channel parameter is specified then the mapping is only applied to slots in the named channel, otherwise the mapping is applied to all channels. The first-specified slot rule that can match a slot takes precedence. Therefore a channel-specific mapping for a given slot should generally appear before a generic mapping for the same slot. In this way a custom mapping may be applied to a particular channel and a default mapping applied to the others.

zpad_slot digits

Pad slot numbers with zeros to make them digits long, which can help to make disk names a consistent length and easier to sort.

multipath yes|no

Specifies whether vdev_id(8) will handle only dm-multipath devices. If set to yes then vdev_id(8) will examine the first running component disk of a dm-multipath device as provided by the driver command to determine the physical path.

topology sas_direct|sas_switch|scsi

Identifies a physical topology that governs how physical paths are mapped to channels:

sas_direct and scsi

channels are uniquely identified by a PCI slot and HBA port number

sas_switch

channels are uniquely identified by a SAS switch port number

phys_per_port num

Specifies the number of PHY devices associated with a SAS HBA port or SAS switch port. vdev_id(8) internally uses this value to determine which HBA or switch port a device is connected to. The default is 4.

slot bay|phy|port|id|lun|bay_lun|ses

Specifies from which element of a SAS identifier the slot number is taken. The default is bay:

bay

read the slot number from the bay identifier.

phy

read the slot number from the phy identifier.

port

use the SAS port as the slot number.

id

use the scsi id as the slot number.

lun

use the scsi lun as the slot number.

bay_lun

read the slot number from the bay identifier and append the lun number. Useful for multi-lun multi-actuator hard drives.

ses

use the SCSI Enclosure Services (SES) enclosure device slot number, as reported by sg_ses(8). Intended for use only on systems where bay is unsupported, noting that port and id may be unstable across disk replacement.

Files

/etc/zfs/vdev_id.conf

The configuration file for vdev_id(8).

Examples

A non-multipath configuration with direct-attached SAS enclosures and an arbitrary slot re-mapping:

multipath     no
topology      sas_direct
phys_per_port 4
slot          bay
#       PCI_SLOT HBA PORT  CHANNEL NAME
channel 85:00.0  1         A
channel 85:00.0  0         B
channel 86:00.0  1         C
channel 86:00.0  0         D
# Custom mapping for Channel A
#    Linux      Mapped
#    Slot       Slot      Channel
slot 1          7         A
slot 2          10        A
slot 3          3         A
slot 4          6         A
# Default mapping for B, C, and D
slot 1          4
slot 2          2
slot 3          1
slot 4          3

A SAS-switch topology. Note, that the channel keyword takes only two arguments in this example:

topology      sas_switch
#       SWITCH PORT  CHANNEL NAME
channel 1            A
channel 2            B
channel 3            C
channel 4            D

A multipath configuration. Note that channel names have multiple definitions - one per physical path:

multipath yes
#       PCI_SLOT HBA PORT  CHANNEL NAME
channel 85:00.0  1         A
channel 85:00.0  0         B
channel 86:00.0  1         A
channel 86:00.0  0         B

A configuration with enclosure_symlinks enabled:

multipath yes
enclosure_symlinks yes
#          PCI_ID      HBA PORT     CHANNEL NAME
channel    05:00.0     1            U
channel    05:00.0     0            L
channel    06:00.0     1            U
channel    06:00.0     0            L

In addition to the disks symlinks, this configuration will create:

/dev/by-enclosure/enc-L0
/dev/by-enclosure/enc-L1
/dev/by-enclosure/enc-U0
/dev/by-enclosure/enc-U1

A configuration using device link aliases:

#     by-vdev
#     name     fully qualified or base name of device link
alias d1       /dev/disk/by-id/wwn-0x5000c5002de3b9ca
alias d2       wwn-0x5000c5002def789e