Serviceguard Extended Distance Cluster (EDC) with VxVM/CVM Mirroring on HP-UX, May 2008

VxVM/CVM features for an EDC

VxVM/CVM has a number of features that are useful in an EDC. The following sections explain these

features and make recommendations on how to use them in an EDC.

Disk naming scheme

VxVM 4.1 offers two different disk naming schemes—operating system naming (OSN) and enclosure-

based naming (EBN).

With OSN (for example, c8t0d2) the VxVM disk name is based on the operating system device file

name by which this disk was known when VxVM first started or when the disk was first attached to the

system. It is difficult to identify the location of a disk by just looking at the device file name.

With EBN, the disks are sequentially named with the prefix of the storage system (enclosure) name.

Figure 3 shows the storage systems that are attached to a system.

Figure 3. List of storage systems / enclosures

$ vxdmpadm listenclosure all

ENCLR_NAME ENCLR_TYPE ENCLR_SNO STATUS ARRAY_TYPE

============================================================================

Disk Disk DISKS CONNECTED Disk

EVA80000 EVA8000 500508B4010203D0 CONNECTED A/A-A-HP

EVA80001 EVA8000 500508B401029730 CONNECTED A/A-A-HP

XP12K0 XP12K 02933 CONNECTED A/A

This node has two EVA 8000s and one XP 12000 attached to it. The line with “Disk” represents the

internal local disks of the system used to boot from. With EBN, the first disk on the XP 12000 would

be named “XP12K0_1” describing (or revealing) its origin/location.

Best practice:

Changing the names of enclosures to include a location string makes it

even easier to determine the location of a disk later.

$ vxdmpadm setattr enclosure XP12K0 name=DC1-XP12k1

$ vxdmpadm setattr enclosure EVA80000 name=DC2-EVA8k1

Configuring enclosures in this way ensures that volumes created using storage from these enclosures

always contain a location string (DC1 and DC2) in their disk (DC1-XP12K0_0) and subdisk

(DC1-XP12K0_0-01) names. This allows administrators to quickly identify the location of a disk by

its name.

VxVM/CVM 5.0 Tip:

Starting with HP Storage Management Suite A.02.00, which includes

VxVM/CVM 5.0, a “siteid” can be assigned to a disk as a method to tag a

disk with its location.

Examples for tagging a disk:

$ vxdisk settag DC1-XP12k1_0 site=DC1

$ vxdisk settag DC2-EVA8k1_0 site=DC2

Chapter 14 “Administering sites and remote mirrors” of the VERITAS

Volume Manager 5.0 Administrator’s Guide provides details about this

feature.