topic Re: EMC POWER PATH in Operating System - HP-UX

EMC POWER PATH

hpuxhelp — Thu, 30 Jan 2003 17:05:02 GMT

Does anyone know on how to set up EMC powerpath on a vg? Does it syntax anything like pvlinks? How does EMC use powerpath to balance I/O?

Re: EMC POWER PATH

Duncan Edmonstone — Thu, 30 Jan 2003 17:16:55 GMT

IIRC you just install powerpath, it makes some kernel changes and requires a reboot, and then you just build your VGs however you like (include/don't include the alternate links in your VG, it doesn't really matter), it takes care of the balancing without any interaction from yourself.

PP has different options on how it load-balances between ports:

1. Active/Standby (as per PVLinks)
2. Active/Active, round-robin IO requests (like VxVM DMP)
3. Active/Active, IO requests are directed to the 'least busy' FA on the Symmm.

HTH

Duncan

Re: EMC POWER PATH

Juan Manuel López — Thu, 30 Jan 2003 17:22:27 GMT

Powerpath is a EMC software that enable to balance the load over both fiber channel to Conectrix Box.
You have to install the software on your machine and it will use both fiber paths.
The most useful command to view the status is:
" powermt display "
Use powermt check to check the fiber devices, delete it and more.
On our system, we discover the new disk attached to a machine with other kind of commands: SIMCLY.
Use symcfg discover to discover the new disk attached.
Use syminq to see the disk your machine can see.
If you have dubs, please, lets me know.
I will give you a hand.
Juanma.

Re: EMC POWER PATH

Sridhar Bhaskarla — Thu, 30 Jan 2003 17:29:59 GMT

Hi,

Powerpath is very easy to setup. Install powerpath (available in .depot format). When "powermt config" is run during the installation or at boot time or through command line it will capture all the disks and put it under it's control and update the configuration.

powermt display will show a brief status of controllers and the disk devices. You can use more options of powermt to drill down further at controller or disk level. Powerpath on the system will automatically load balance the paths if setup by default by doing IO in roundrobin fashion.

powermt without any option will display help.

-Sri

Re: EMC POWER PATH

Jordan Bean — Thu, 30 Jan 2003 20:34:58 GMT

As already stated, PowerPath doesn't care about alternate links. However, if your systems boot off the Symmetrix (as do ours), then it is very important to properly configure the pv links only to ensure that the hosts can boot on auxiliary paths and activate the volume groups if the primaries are unavailable. Note: This is only necessary if the hosts require reboots during such channel failure... Of course, you can swap the cables or HBAs if necessary.