Multipath:
A simple example would be a SCSI disk connected to two SCSI controllers on the same computer or a disk connected to two Fibre Channel ports. Should one controller, port or switch fail, the operating system can route I/O through the remaining controller transparently to the application, with no changes visible to the applications, other than perhaps incremental latency.
Features of Multipath:
* Dynamic load balancing
* Traffic shaping
* Automatic path management
* Dynamic reconfiguration
How to find multipath on hp ux ??
1.pvlinks
# strings /etc/lvmtab
# vgdisplay -v vgname
2.Native Multipathing (11.31) (agile device name)
# ioscan -m dsf h/w address
Examble : ioscan -m dsf/dev/rdisk/disk586
Persistent DSF Legacy DSF(s)
=============================================
/dev/rdisk/disk586 /dev/rdsk/c15t0d0
/dev/rdsk/c16t0d0
# scsimgr -D lun_map (which will give the number of paths to that lun)
# ioscan -kfnNC (will show the persistent device file in 11.31)
# evainfo (EVA) and xpinfo (XP) - commands will show the multipaths for luns.
A simple example would be a SCSI disk connected to two SCSI controllers on the same computer or a disk connected to two Fibre Channel ports. Should one controller, port or switch fail, the operating system can route I/O through the remaining controller transparently to the application, with no changes visible to the applications, other than perhaps incremental latency.
Features of Multipath:
* Dynamic load balancing
* Traffic shaping
* Automatic path management
* Dynamic reconfiguration
How to find multipath on hp ux ??
1.pvlinks
# strings /etc/lvmtab
# vgdisplay -v vgname
2.Native Multipathing (11.31) (agile device name)
# ioscan -m dsf h/w address
Examble : ioscan -m dsf/dev/rdisk/disk586
Persistent DSF Legacy DSF(s)
=============================================
/dev/rdisk/disk586 /dev/rdsk/c15t0d0
/dev/rdsk/c16t0d0
# scsimgr -D lun_map (which will give the number of paths to that lun)
# ioscan -kfnNC (will show the persistent device file in 11.31)
# evainfo (EVA) and xpinfo (XP) - commands will show the multipaths for luns.
1 Comments
Great post.
ReplyDeleteI have also found for fiber, using a combination of "fcmsutil" and "ioscan" can give you a lot of great detail:
e.g. on a system I have here
# fcmsutil /dev/fcd2
..
Hardware Path is = 0/3/1/0
..
# fcmsutil /dev/fcd3
..
Hardware Path is = 0/3/1/1
..
Then
# ioscan -f -n -C disk
..
disk 6 0/3/1/0.1.7.0.0.0.0 sdisk CLAIMED DEVICE IBM 1722-600
/dev/dsk/c9t0d0 /dev/rdsk/c9t0d0
..
disk 30 0/3/1/1.1.7.0.0.0.0 sdisk CLAIMED DEVICE IBM 1722-600
/dev/dsk/c8t0d0 /dev/rdsk/c8t0d0
..
So two disks, one each on the hardware paths for the HBAs
Finally
# ioscan -f -n -N -C disk
..
disk 46 64000/0xfa00/0xe esdisk CLAIMED DEVICE IBM 1722-600
/dev/disk/disk46 /dev/rdisk/disk46
..
That's the only IBM disk that shows up and it is the combined path for the two disks previous
Anyway.. :)
Thanks!