HP-UX Logical Volume Manager and MirrorDisk/UX Release Notes (September 2009)

However, if you want backward-compatible PVLink behavior, you must use legacy device special
files for physical volumes, and disable the mass storage stack multipathing for those physical
volumes. To disable multipathing on legacy device special files, use the scsimgr command to
configure a global device tunable called leg_mpath_enable.
For each multipathed disk, enter the following command:
# scsimgr save_attr -D /dev/rdisk/diskn -a leg_mpath_enable=false
Alternatively, you can disable multipathing for all legacy device files with this command:
# scsimgr save_attr -a leg_mpath_enable=false
Note that this has no effect on multipathing through persistent device special files. For more
information, see scsimgr(1M).
Moving Volume Groups from HP-UX 11i v3 to Previous HP-UX Releases
If a volume group used on HP-UX 11i v3 is accessed from a system running a previous release
of HP-UX 11i, you might encounter these compatibility issues:
• Version 2.x volume groups: As noted in “Version 2.1 Volume Groups” (page 10), Version
2.x volume groups are not recognized on previous releases of HP-UX.
• Logical volumes larger than 2 TB: Releases prior to HP-UX 11i v3 can only access data
within the first 2 TB of a logical volume. If a logical volume larger than 2 TB is created on
HP-UX 11i v3, its use is not recommended on any previous HP-UX release. The volume
group can be activated and the logical volume can be used, but any data in that logical
volume beyond 2 TB will be inaccessible.
NOTE: Patches PHKL_36745, PHCO_36744, and PHCO_37939 resolve this compatibility
issue for HP-UX 11i v2. Installing these patches enables the creation and use of logical
volumes up to 16 TB.
• Striped Mirrors: Releases prior to HP-UX 11i v3 only support extent-based striping via the
-D option to lvcreate. If a logical volume using simultaneous mirroring and
non-extent-based striping is created on HP-UX 11i v3, attempts to import or activate its
associated volume group will fail on a previous HP-UX release. To import the volume group,
you must remove the incompatible logical volumes or reduce them to a single mirror.
NOTE: Patches PHKL_36745, PHCO_36744, and PHCO_37939 resolve this compatibility
issue for HP-UX 11i v2. Installing these patches enables the creation and use of striped
mirrors.
• Mirror Write Cache (MWC): When a volume group containing a logical volume using the
Mirror Write Cache is activated on HP-UX 11i v3, its Mirror Write Cache format is converted
to a new format. Importing or activating the volume group on a previous HP-UX release
does not recognize the new format and triggers a full resynchronization of the mirrors.
NOTE: Patch PHKL_36244 adds support for the new MWC format to HP-UX 11i v2.
Installing this patch avoids the unnecessary resynchronization.
As of this writing, larger logical volumes and striped mirrors are only available on HP-UX 11i
v3 and HP-UX 11i v2 (with patches). For up-to-the-moment information, contact your
Hewlett-Packard support representative or consult the Hewlett-Packard IT Resource Center site:
http://itrc.hp.com (Americas and Asia Pacific) or http://europe.itrc.hp.com (Europe) for LVM
patches.
Compatibility Issues 11