HP StorageWorks XP10000 Disk Array - Manual (Page 142)

CAUTION:
Note the following points when you perform a Volume Manager operation using a path-defined LDEV:
• If a path is defined from a Windows 2000, Windows Server 2003, or AIX 5.2 host to an LDEV, you
can use the LDEV for Volume Manager operations using a path-defined LDEV. However, if a path
is defined from a host running another operating system to an LDEV, you cannot use the LDEV for
Volume Manager operations using a path-defined LDEV.
• If a path is defined from a Windows 2000 or Windows Server 2003 host to an LDEV and you
want to perform a Volume Manager operation that handles this path-defined LDEV, ensure that the
Windows host's host mode is 2C (Windows Extension). If the host mode is not 2C, change the host
mode to 2C before performing the Volume Manager operation.
Overview of Custom Volume Size
This section describes the Custom Volume Size (CVS) function, configuring CVS, and requirements of the
storage subsystem ID (SSID). CVS operations include:
• Viewing concatenated parity groups
• Converting logical volumes to space
• Creating CVS volumes (Install CV operation)
• Deleting CVS volumes
• Converting CVs back to FVs (Volume Initialize operation)
• Re-creating CVs after initializing the VDEV (Make Volume operation)
CVS function
CVS works on each VDEV that consists of a group of logical volumes (LDEVs or LUs) in a parity group.
Usually, one VDEV consists of some fixed volumes (FV) and some free space. The emulation type
determines the number of fixed volumes. A CVS volume usually consists of at least one fixed volume (FV),
one or more customized volumes (CVs), and some free space. CVS allows you to configure variable-size
volumes, which are usually smaller than normal (fixed-size) volumes. Therefore, if several frequently
accessed files are located in the same logical volume, use CVS to reduce conflicts by splitting the logical
volumes and scattering the files, although there are some instances where access is delayed while a file is
being accessed. This can improve data accessing performance. CVS can also divide a logical volume
into smaller ones for a command device, which efficiently exploits the disk's capacity.
CVS operations include: Volume to Space, Install CV, Volume Initialize, and Make Volume. The Volume
to Space function formats one or more LDEVs on a selected Virtual Device (VDEV) into free space. That
free space can either be used to install one or more variable-sized volumes (CVs) using the Install CV
function, or left as free space for future use. The Volume Initialize function de-installs all variable sized
volumes (CVs) under a CVS volume, and reformats the CVS volume as a normal volume (VDEV). The
Make Volume function clears all variable-sized volumes (CVs) under a CVS volume and creates an initial
volume (VDEV) consisting of the new user-defined CVs.
For an overview of how the Volume Initialize function works, see
Figure 77 . For an overview of how
the Make Volume function works, see Figure 78 .
142 Overview of Volume Manager and Custom Volume Size