hardware path to SAN attached tape drives

[Kurt Beyers.]

Hi,

I've got a MSL6030 connected to a SAN and a few Windows2003 servers are attached to the SAN as well by means of Emulex Lightpulse PCI Fibre Channel HBA.

The two physical nodes of a MCSC cluster see the same physical drive through another hardware path:

-scsi2:1:2:1C on server 1
-scsi3:1:2:1C on server 2

How do I modify the hadware path on one of the servers so that it is the same on both physical nodes, eg. scsi2:1:2:1C. Is this done somewhere with the tool lputilnt?

For the backup of the virtual servers, the hardware path of the tape drive must be the same on both nodes. Else the backup will fail in case of a failover.

best regards,
Kurt

[Uwe Zessin]

Kurt,
what is the first number after "scsi"? The port number of the adapter?

It looks like the servers are not built symetrically. In that case I am afraid you have to lay your hand on the hardware.

[Kurt Beyers.]

Uwe,

The number that differs would be the slot/bus number of the Emulex cards. Can this be changed during the booting of the server, you can go into a BIOS setup program here.

Or must the cards be changed physically in the server. Or are they connected to another SAN swith and must these connections be switched?

We're still in a lab phase, so hardware changes can still be planned without too much unconvenience.

best regards,
Kurt

[Steven Clementi · Accepted solution]

Your probably better off just making the hba's sit in the same slots as it sounds like you currently have one in a different slot than the other server... OR, perhaps you have your fibre cables switched.

e.g.

both servers has hba's in Slot 2 and 3

Server A's slot 2 is connected to the A fabric and Server B's Slot 2 is connected to the B fabric. Swap the cables and you should be ok. (This looks like what you are seeing, but can't tell without a cabling diagram)



Steven

[Stuart Whitby]

The config program for the Emulex card will allow you to specify persistent bindings. This should allow you to fix the SCSI IDs on the drives rather than having them show up differently each time. With this set, my guess is that you will have the same hardware path on the drives themselves.

The main thing I see as a potential problem is that the bus number (SCSI ID on the Emulex card) may also need to be fixed. I'm sure that can also be done within the card config, I just can't say for sure how. With this fixed, you should get a consistent path to the tape drives, and with the bus numbers fixed, these should be the same on both systems.

[Steven Clementi]

You wouldn't be able to change te Bus ID since each slot has an associated bus id which is generally not changeable. It is hard wired on the mobo, usually.

Persistant bindings can also be used to "keep" the config the same across reboots and SAN device additions.

If you only have one library/drive, then it would not matter too much, since only that one drive is available.

I know veritas has a big issue when the bus/scsi id's change on a tape drive. I could see Legato networker having an issue as well. Not sure about DP or other backup products.


Steven