HP-UX 11i v3 LVM New Features in HP-UX 11i v3 (September 2009)

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Mirror Write Cache (MWC) Enhancements
ly records this
activity in an on-disk data structure. An extra disk write is required for every mirrored write not already recorded
WC to resynchronize
logical volume I/O
performance by allowing more concurrent writes. MWC has also been enhanced to support large I/O sizes.
nd, respectively. For
ange(1M).
ted with
vgchange –a s) of version 1.0 and 2.0
must have the consistency recovery set to NOMWC or NONE. Versions 1.0 and 2.0 do not support MWC for
longing to shared volume groups.
es belonging to version
the MWC is activated
v3, its MWC format is converted. Any subsequent activation of this volume group on previous
n of the entire logical
d, activation of the
is happens during a Serviceguard rolling
eleases might be enhanced to recognize the new MWC format; contact your
tative for up-to-the-moment information, or consult the Hewlett-Packard IT
Performance Improvements
The MWC allows a fast resynchronization of data following a system crash or failure.
The MWC keeps track of where I/O writes are occurring on the volume group and periodical
on the physical volume. Upon system reboot after crash, the operating system uses the M
inconsistent data blocks quickly.
In HP-UX 11i v3, the MWC is larger in size than in previous releases. This leads to a better
To enable or disable MWC, use the
-M y or -M n option with lvcreate or lvchange comma
more information on MWC, see lvcreate(1M) and lvch
Logical volumes belonging to shared volume groups (those activa
logical volumes be
With the September 2008 release of HP-UX 11i v3, LVM supports MWC for logical volum
2.1 shared volume groups. This ensures faster recovery following a system crash.
Compatibility Note:
When a volume group containing a logical volume (created on pre-11i v3 releases) using
on HP-UX 11i
releases do not recognize the new MWC format and LVM performs a full resynchronizatio
volume. But if the logical volumes are marked “NOMWC” and the logical volume is synce
volume group on previous releases avoids full resynchronization. Note th
update configuration. Previous r
Hewlett-Packard support represen
Resource Center site: http://itrc.hp.com
(Americas and Asia Pacific) or http://europe.itrc.hp.com (Europe) for
orted on HP-UX 11i v2 with the patch
PHKL_36244 or any superseding patch. With the patch PHKL_36244 or any superseding patch installed on HP-
O sizes (up to the extent size). As I/O requests do not need to be split into smaller
chunks, the I/O throughput is improved by issuing reads and writes of larger sizes through LVM.
Note that the actual I/O size might be limited by the interface card.
For more information, see the “HP-UX System Administrator's Guide: Logical Volume Management” available at
http://docs.hp.com/en/oshpux11iv3.html#LVM%20Volume%20Manager
LVM patches.
NOTE: The new format of MWC introduced in HP-UX 11i v3 is supp
UX 11i v2, the new format of MWC is recognized and used to perform the recovery.
LVM Support for Large I/O Sizes
LVM now supports larger I/
Also see the The Next Generation Mass Storage Stack
whitepaper.
HP recommends you see the whitepaper for information on benefits and capabilities introduced in the New Mass
Storage Stack in HP-UX 11i v3.