vdev_id.conf - Configuration file for vdev_id 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 - the name of the link to the device that will by created in /dev/disk/by-vdev. devlink - 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 of: /dev/by-enclosure/<prefix>-<channel><num> Defaults to "enc" if not specified.

pci_slot - specifies the PCI SLOT of the HBA hosting the disk enclosure being mapped, as found in the output of lspci (8). This argument is not used in sas_switch mode. port - specifies the numeric identifier of the HBA or SAS switch port connected to the disk enclosure being mapped. name - specifies the name of the channel.

slot <old> <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.

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 listed by the multipath (8) command to determine the physical path.

topology <sas_direct|sas_switch> Identifies a physical topology that governs how physical paths are mapped to channels. sas_direct - in this mode a channel is uniquely identified by a PCI slot and a HBA port number sas_switch - in this mode a channel is 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|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. ses - use the SCSI Enclosure Services (SES) enclosure device slot number, as reported by sg_ses (8). This is intended for use only on systems where bay is unsupported, noting that port and id may be unstable across disk replacement.

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

/etc/zfs/vdev_id.conf The configuration file for vdev_id (8).

vdev_id (8)