Alternate links

[Keith Floyd]

Hi

I am connected to EMC disks via direct fibre cable.
I will be configuring data vol etc on them
I will in near future be re-connecting via fibre hub and dual paths
I would like to then force access of half disks down one path half down the other.
What will be the best way to convert the device files

Thanks
Keith

[James R. Ferguson · Accepted solution]

Keith:

Device files should be created when you reboot following the new connection setup. Then extend the new alternate path into the volume group(s). When you have all the disks you want with primary and alternate links (the alternates all being on one path), vgreduce the primary path out of half the disk in question. This will cause an automatic switch to the alternate link, making it the primary. Then, lastly, vgextend the paths you first reduced, making them the alternate links.

...JRF...

[Timothy Czarnik]

Keith,

FYI, don't do this using SAM. SAM is not certified to use EMC/PV links, and we found this out the hard way. Go command line, and map out what you want to do on paper (thats what I do, but I'm paranoid).

Awhile back we had a novice use SAM to create a VG with EMC disks. SAM allowed them to put a device in one VG and its alternate link into another. Sooner or later, bad things will happen (unless you consider rebuilding databases a good thing).

Just my 2 cents... good luck!

-Tim