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Manual: Volume Manager 4.1 Administrator's Guide   

Changing the Disk-Naming Scheme

Note   Note    Devices with very long device names (for example, Fibre Channel devices that include worldwide name (WWN) identifiers) are always represented by enclosure-based names. The operation in this section has no effect on such devices.

You can either use enclosure-based naming for disks or the operating system's naming scheme (such as c#t#d#). Select menu item 20 from the vxdiskadm main menu to change the disk-naming scheme that you want VxVM to use. When prompted, enter y to change the naming scheme. This restarts the vxconfig daemon to bring the new disk naming scheme into effect.

Alternatively, you can change the naming scheme from the command line. The following commands select enclosure-based and operating system-based naming respectively:

vxddladm set namingscheme=ebn
vxddladm set namingscheme=osn

The change is immediate whichever method you use.

Changing Device Naming for TPD-Controlled Enclosures

Note   Note    This feature is available only if the default disk-naming scheme is set to use operating system-based naming, and the TPD-controlled enclosure does not contain fabric disks.

For disk enclosures that are controlled by third-party drivers (TPD) whose coexistence is supported by an appropriate ASL, the default behavior is to assign device names that are based on the TPD-assigned node names. You can use the vxdmpadm command to switch between these names and the device names that are known to the operating system:

vxdmpadm setattr enclosure enclosure tpdmode=native|pseudo

The argument to the tpdmode attribute selects names that are based on those used by the operating system (native), or TPD-assigned node names (pseudo).

The use of this command to change between TPD and operating system-based naming is illustrated in the following example for the enclosure named EMC0:

vxdisk list
DEVICE          TYPE         DISK      GROUP      STATUS
emcpower10          auto:hpdisk         disk1      mydg      online
emcpower11          auto:hpdisk         disk2      mydg      online
emcpower12          auto:hpdisk         disk3      mydg      online
emcpower13          auto:hpdisk         disk4      mydg      online
emcpower14          auto:hpdisk         disk5      mydg      online
emcpower15          auto:hpdisk         disk6      mydg      online
emcpower16          auto:hpdisk         disk7      mydg      online
emcpower17          auto:hpdisk         disk8      mydg      online
emcpower18          auto:hpdisk         disk9      mydg      online
emcpower19          auto:hpdisk         disk10      mydg      online
vxdmpadm setattr enclosure EMC0 tpdmode=native
vxdisk list
DEVICE          TYPE         DISK      GROUP      STATUS
c6t0d10          auto:hpdisk         disk1      mydg      online
c6t0d11          auto:hpdisk         disk2      mydg      online
c6t0d12          auto:hpdisk         disk3      mydg      online
c6t0d13          auto:hpdisk         disk4      mydg      online
c6t0d14          auto:hpdisk         disk5      mydg      online
c6t0d15          auto:hpdisk         disk6      mydg      online
c6t0d16          auto:hpdisk         disk7      mydg      online
c6t0d17          auto:hpdisk         disk8      mydg      online
c6t0d18          auto:hpdisk         disk9      mydg      online
c6t0d19          auto:hpdisk         disk10      mydg      online

If tpdmode is set to native, the path with the smallest device number is displayed.

Discovering the Association between Enclosure-Based Disk Names and OS-Based Disk Names

If you enable enclosure-based naming, and use the vxprint command to display the structure of a volume, it shows enclosure-based disk device names (disk access names) rather than c#t#d# names. To discover the c#t#d# names that are associated with a given enclosure-based disk name, use either of the following commands:

vxdisk list enclosure-based_name
vxdmpadm getsubpaths dmpnodename=enclosure-based_name

For example, to find the physical device that is associated with disk ENC0_21, the appropriate commands would be:

vxdisk list ENC0_21
vxdmpadm getsubpaths dmpnodename=ENC0_21

To obtain the full pathname for the block and character disk device from these commands, append the displayed device name to /dev/vx/dmp or /dev/vx/rdmp.

Regenerating the Persistent Device Name Database

The persistent device naming feature, introduced in VxVM 4.1, makes the names of disk devices persistent across system reboots. If operating system-based naming is selected, each disk name is usually set to the name of one of the paths to the disk. After hardware reconfiguration and a subsequent reboot, the operating system may generate different names for the paths to the disks. As DDL assigns persistent disk names using the persistent device name database that was generated during a previous boot session, the disk names may no longer correspond to the actual paths. This does not prevent the disks from being used, but the association between the disk name and one of its paths is lost.

To find the relationship between a disk and its paths, run one of the following commands:

vxdmpadm getsubpaths dmpnodename=disk_access_name
vxdisk list disk_access_name

If you want to update the disk names so that they correspond to the new path names, perform the following steps:

  1. Remove the file that contains the existing persistent device name database:
    rm /etc/vx/
  2. Restart the VxVM configuration demon:
    vxconfigd -k

    This regenerates the persistent name database.

Issues Regarding Persistent Simple/Nopriv Disks with Enclosure-Based Naming

If you change from c#t#d# based naming to enclosure-based naming, persistent simple or nopriv disks may be put in the "error" state and cause VxVM objects on those disks to fail. If this happens, use the following procedures to correct the problem:

These procedures use the vxdarestore utility to handle errors in persistent simple and nopriv disks that arise from changing to the enclosure-based naming scheme. You do not need to perform either procedure if the devices on which any simple or nopriv disks are present are not automatically configured by VxVM (for example, non-standard disk devices such as ramdisks).

Note   Note    The disk access records for simple disks are either persistent or non-persistent. The disk access record for a persistent simple disk is stored in the disk's private region. The disk access record for a non-persistent simple disk is automatically configured in memory at VxVM startup. A simple disk has a non-persistent disk access record if autoconfig is included in the flags field that is displayed by the vxdisk list disk_access_name command. If the autoconfig flag is not present, the disk access record is persistent. Nopriv disks are always persistent.

Note   Note    You cannot run vxdarestore if c#t#d# naming is in use. Additionally, vxdarestore does not handle failures on persistent simple/nopriv disks that are caused by renaming enclosures, by hardware reconfiguration that changes device names. or by removing support from the JBOD category for disks that belong to a particular vendor when enclosure-based naming is in use.

For more information about the vxdarestore command, see the vxdarestore(1M) manual page.

Persistent Simple/Nopriv Disks in the Boot Disk Group

If all persistent simple and nopriv disks in the boot disk group (usually aliased as bootdg) go into the error state and the vxconfigd daemon is disabled after the naming scheme change, perform the following steps:

  1. Use vxdiskadm to change back to c#t#d# naming.
  2. Enter the following command to restart the VxVM configuration daemon:
    vxconfigd -kr reset
  3. If you want to use enclosure-based naming, use vxdiskadm to add a non-persistent simple disk to the bootdg disk group, change back to the enclosure-based naming scheme, and then run the following command:
    Note   Note    If not all the disks in bootdg go into the error state, you need only run vxdarestore to restore the disks that are in the error state and the objects that they contain.

Persistent Simple/Nopriv Disks in Non-Boot Disk Groups

If an imported disk group other than bootdg, consisting only of persistent simple and/or nopriv disks, is put in the "online dgdisabled" state after the change to the enclosure-based naming scheme, perform the following steps:

  1. Deport the disk group using the following command:
    vxdg deport diskgroup
  2. Use the vxdarestore command to restore the failed disks, and to recover the objects on those disks:
  3. Re-import the disk group using the following command:
    vxdg import diskgroup
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Product: Volume Manager Guides  
Manual: Volume Manager 4.1 Administrator's Guide  
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