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What would happen if I added 4 paths to same disk (only 2 HBAs)

Joe Bruno
Occasional Contributor

What would happen if I added 4 paths to same disk (only 2 HBAs)

I'm going to be switching the ports on which my Unix server is commincating to the disks on the XP-512. I'm about to assign 2 more SCSI paths to the same disks that are on PORTS 1A and 2A. The new paths are going to be on 1C and 2C. Then I plan in doing a series of vgextends and vgreduces to remove the paths and have the new paths take their place. Is there anything wrong with this logic?

Thanks in advance.
2 REPLIES
Jerome Baron
Respected Contributor

Re: What would happen if I added 4 paths to same disk (only 2 HBAs)

Hi,

You can done vgexport and vgimport with the new device file.

Regards,
Jerome
Eugeny Brychkov
Honored Contributor

Re: What would happen if I added 4 paths to same disk (only 2 HBAs)

Logic is correct. If you have more than one path to the same LUN, then adding these paths to VG will add alternate paths to physical volume within VG. But only one path can be primary.
When you add one more path with vgextend then this path became last alternate path. If you want this newly added path to be primary, you should add it, and then remove and add all the paths which are 'above' this path. Doing this way you'll move paths added after this one as alternate ones, and finally this path will be the first - primary
Eugeny