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fcid and OS device path

robert.ho
Level 1
Level 1

Dear all,

In my environment, there are 2 x MDS 9513, EMC storage, Solaris, Linux and ESX 3.x hosts. Currently they are plugging in a same vsan. For some reason, I have to relocate all of them to another vsan. In my testing env, MDS9216, I found that the fcid changes after the vsan move even I have enable persistent fcid.

Will the OS device path change after the vsan migration? If it changes, will the OS fix it automatically?

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Accepted Solutions

stephen2615
Level 3
Level 3

The fcid is dependent on the domain id of the vsan. So if your old VSAN has a domain id of 10 and the new had a domain id of 20, anything you plug into that new VSAN will have 0x20.... instead of 0x10..... The good news (as far as I know) is that Solaris, later versions of Linux/ESX don't have any issues with the fcid changing. The hosts might do a dynamic reconfigure but I doubt you will notice anything. If you had AIX, thats another story. Heck, even Windows can handle the fcid change. The only time I have seen devices paths change was when I changed the connection to HBA ports and that was a physical change not a logical which will happen with the switch. Solaris automatically fixed those device paths when I did it.

Stephen

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3 Replies 3

stephen2615
Level 3
Level 3

The fcid is dependent on the domain id of the vsan. So if your old VSAN has a domain id of 10 and the new had a domain id of 20, anything you plug into that new VSAN will have 0x20.... instead of 0x10..... The good news (as far as I know) is that Solaris, later versions of Linux/ESX don't have any issues with the fcid changing. The hosts might do a dynamic reconfigure but I doubt you will notice anything. If you had AIX, thats another story. Heck, even Windows can handle the fcid change. The only time I have seen devices paths change was when I changed the connection to HBA ports and that was a physical change not a logical which will happen with the switch. Solaris automatically fixed those device paths when I did it.

Stephen

yeah, Stephen, you are rite.

how come i forgot the domain id of the vsan? better to dig out the mds 101 to have a look. :)

Thanks for your help!

Stephen,

Just need to correct your comments regarding AIX.

Early versions of AIX did not support FCID changes, and required some manual actions to pick up the change.

AIX has though for some time supported 'dynamic Tracking' which allows the FCID to change without any user action.

There are still some OS's out there though that do not support such changes.

For the purpose of this VSAN migrate, it is possible to make the VSAN domain ID's the same, then by setting persistent FCIDs and allocating the same FCID as the previous VSAN you would have no exposures at all for any OS.

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