HP-UX Logical Volume Manager and MirrorDisk/UX Release Notes (September 2008)

Required Disk Space
Since LVM is installed with the HP-UX 11i v3 operating environment, it consumes no additional
disk space.
MirrorDisk/UX consumes no additional disk space aside from a license key.
Compatibility Issues
This release is specific for HP-UX 11i v3 (B.11.31). The following compatibility issues exist in the
September 2008 release of HP-UX 11i v3.
Version 2.1 Volume Groups
• Version 2.1 volume groups are not recognized on previous releases of HP-UX, including
previous versions of HP-UX 11i v3. Version 1.0 volume groups are supported on all supported
versions of HP-UX, including 11i v1, 11i v2, and 11i v3.
• There is currently no method for converting a volume group in place from one version to
another. To migrate a volume group to a different version, you must create a new volume
group and copy the data.
• The following HP-UX products do not currently support Version 2.0 or Version 2.1 volume
groups:
— HP Process Resource Manager (HP PRM)
— Encrypted Volume and File System (EVFS v1.0)
These products plan to add support of Version 2.x volume groups. For the most recent
information on these products, see the IT Resource Center (ITRC) at http://itrc.hp.com, or
consult the release notes for the specific product.
Moving from HP-UX 11i v2 to HP-UX 11i v3
If you are migrating a system from HP-UX 11i v2 to HP-UX 11i v3, please refer to the LVM
migration white paper described in the “Related Documentation” section. It contains information
on migrating an LVM configuration from the legacy naming model to the agile naming model.
Existing LVM configurations created on HP-UX 11i v2 continue to work on HP-UX 11i v3 under
the legacy naming model. However, there is a change in behavior for Alternate Links (PVLinks):
In HP-UX 11i v3, management of multi-pathed devices is available outside of LVM using the
next generation mass storage stack. By default, the next generation mass storage stack distributes
I/O requests across all available paths to a multi-pathed disk, even when using legacy device
special files. Using LVM with persistent or legacy device special files may cause I/O requests to
be sent across alternate links, even if the links are not configured as PVLinks; this should not
introduce any errors, but it does differ from PVLink behavior in previous releases.
HP recommends converting volume groups with multi-pathed disks to persistent device special
files and native multi-pathing, as described in the migration white paper in “Related
Documentation”.
However, if you want backward-compatible PVLink behavior, you must use legacy device special
files for physical volumes, and disable the mass storage stack multi-pathing for those physical
volumes. To disable multi-pathing on legacy device special files, use the scsimgr command to
configure a global device tunable called leg_mpath_enable.
For each multi-pathed disk, enter the following command:
# scsimgr save_attr -D /dev/rdisk/diskn -a leg_mpath_enable=false
Alternatively, you can disable multi-pathing for all legacy device files with this command:
# scsimgr save_attr -a leg_mpath_enable=false
Note that this has no effect on multi-pathing through persistent device special files. For more
information, see scsimgr(1M).
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