HP-UX HB v13.00 Ch-13 - LVM

HP-UX Handbook – Rev 13.00 Page 77 (of 110)
Chapter 13 LVM
October 29, 2013
 Path switch options of the pvchange (-s and –S options) command do not switch
links or stop I/O operations as they did in earlier releases. In order to disable I/O
operations on a given path, use the scsimgr command (scsimgr [-f] disable
Lunpath).
 While LVM alternate link functionality supports up to 8 paths to a physical
volume, mass storage stack’s native multipathing feature can support up to 32
lunpaths.
If legacy LVM alternate link functionality is preferred over the mass storage stack’s
native multi pathing functionality, the native multipathing feature can be disabled using
the scsimgr command.
The following example shows how to enable legacy LVM alternate link functionality in a
backward compatible manner. In this example, the vg01 is configured with a single
persistent DSF:
Example:
1. Get a list of DSFs configured in the volume group:
#vgdisplay –v –F vg01 | grep pv_name
2. Find legacy DSFs corresponding to the persistent DSF:
# ioscan –m dsf /dev/disk/disk5
Persistent DSF Legacy DSF(s)
/dev/disk/disk5 /dev/dsk/c2t1d0
/dev/dsk/c3t1d0
3. Add legacy DSFs as alternate links to the persistent DSF:
# vgextend vg01 /dev/dsk/c2t1d0 /dev/dsk/c3t1d0
4. Remove the persistent DSF from the volume group:
# vgreduce vg01 /dev/disk/disk5
5. Disable native multipathing through legacy DSFs:
scsimgr command can be run in any of the two ways listed below:
 Disable native multipathing for a specific LUN in a non-persistent way:
#scsimgr set_attr –D /dev/rdisk/disk5 –a leg_mpath_enable=false
Value of attribute leg_mpath_enable set successfully
 Disable native multipathing globally for all LUNs in the system, in a non-
persistent way:
#scsimgr set_attr –a leg_mpath_enable=false
Value of attribute leg_mpath_enable set successfully
6. Verify the resaulting configuration: