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

1
0
For more information, see the LVM Volume Group Quiesce/Resume whitepaper.
Boot Resiliency
Root volume group scanning is a new LVM feature in HP-UX 11i v3. The feature can prevent boot failures that can
n information is incorrect or out-
s are:
• The root volume group is configured using legacy DSFs representing the devices in a Storage Area
ch situations; LVM now scans all the
disks to identify the ones belonging to the root volume group and retries activation. If the activation succeeds, it is
ut of sync with the
river prints a warning
:
“LV activation required a scan. The PV information in the on-disk
BDRA from the system's current IO configuration. To update the
ate the on-disk
root VG name is /dev/vg00:
ot volume group are not available but the quorum is met, no root volume
group scan is performed. Also, during a single user mode boot with
-is or maintenance mode boot with -lm, root
Note: This feature is enhanced further in the September 2008 release of HP-UX 11i v3. For more information,
nfiguration Self Healing
occur on prior HP-UX releases.
During boot, the root volume group activation can fail if the LVM boot configuratio
auseof-date with the systems current I/O configuration. Two possible c
Network(SAN) and the SAN is reconfigured such that DSFs of the devices changed.
• The root disk is relocated to a different slot such that the DSF name changes.
With the new root volume group scanning, LVM automatically handles su
likely that the LVM in-memory boot configuration information for the root volume group is o
DSF in the /etc/lvmtab for the root volume group. To assist recovery in this case, the LVM d
message to the console and logs into /var/adm/syslog/syslog.log to the effect as follows
M: WARNING: Root VG
may be out-of-date
on-disk BDRA, first update /etc/lvmtab using vgscan(1M), then upd
BDRA using lvlnboot(1M).
For example, if the
vgscan -k -f /dev/vg00
lvlnboot -R /dev/vg00”
In case some physical volumes in the ro
volume group scanning is skipped.
see the “Boot Disk Co
” section.
an the
t possible stripe size).
monly referred to as striping, refers to the segmentation of logical sequences of data across disks. RAID
1, commonly referred to as mirroring, refers to creating exact copies of logical sequences of data. When
implemented in a device hardware, RAID 10 (or RAID 1+0) and RAID 01 (or RAID 0+1) are nested RAID levels. The
difference between RAID 0+1 and RAID 1+0 is the location of each RAID system — RAID 0+1 is a mirror of
stripes whereas RAID 1+0 is a stripe of mirrors. Figure 1 shows the RAID 10 and RAID 01 configurations (A1, A2...Ax
are stripe chunks of a logical volume).
With a hardware-based RAID 10 configuration, I/O operations are striped first then each strip is mirrored. With
hardware-based RAID 01, I/Os are mirrored first then striped. RAID 10 and RAID 01 can have the same physical
disk layout.
Striped and Mirrored Logical Volumes
HP-UX LVM now introduces support for striped and mirrored logical volumes at a smaller granularity th
extent size (4KB is the smalles
RAID 1+0 and RAID 0+1
RAID 0, com