[cdelgadop]

Hi

My customer wants to change some servers form old SAN switches to new IBM Director ones and want to make it with less impact as posibles for operations.

Servers or partitions running AIX are connected to a SAN (using two FC adapters) with a IBM DS4800 Storage subsystem, so RDAC software is running to provide failover and load balancing. Following what we have planned:

1- Identify both dac devices and use fget_config to know the relationship between these and LUNs in the DS4800.
2- Modify preferred path so all LUNs use the same FC adapter in the AIX server. This way we make the traffic goes for one path. Record information about fiber adapters (WWNN and so on).
3- Delete the dac device as well as the fcs one from the ODM with the rmdev -Rdl command.
4- Unplug the old fiber and connect the new one to the Director. Run cfgmgr so WWNN appears in the switch and make the new zone connecting with LUNs in the Ds4900.
5- Run cfgmgr once again, it's supposed dac devices will be created and path to the LUNs using the Director. itsn't it ??

Then i can modify the preferred path so all LUNs use the new path and chenge the remaining dac using the same procedure.

What fo you think about this procedure ??,

Thanks in advanced

[ross.mather]

What you suggest will work, I'd however - switch over to the new cards before I delete the old ones - just in case I want to go back.

Just seems that by cleaning up as you go rather than when you are done you are adding steps and making your backout options more complex.

[cdelgadop]

Hi Ross.

Thanks for your answer.

I'm really not changing adapters but using the same ones, just changing fiber pathcords already connected to the new Director. After connecting them i need the WWNN of each fcs device to be active in the director in order to make zones, i have seen sometimes situations where i need to delete and config on order to get this info active.

Problem of using this storage device (DS4xxx series) is the RDAC itself. Working with IBM SDD, EMC2 Powerpath and Hitachi dlm disks is quite easy because they allow for the inactivation of the entire path so you can even delete the Fiber Channel adapter with all its childrens and reconfig again without having to move LUNs from preferred and alternate paths.

Your comments

[ross.mather]

I think you could be right. RDAC is always a bit funny.

[cdelgadop]

Hi Ross

Actually we have problems changing servers from Swicht to directors. We ran fget_config command in order to identify LUNs as well as dac devices (and their corresponding fcs adapters), then we used the Storage Manager in order to move all LUNs to one path, let's say dac0. When ran fget_config we saw all LUNs in the dac0, however still some disks were seen by both fcs adapters so we ran cfgmgr so all hdisk devices were seen by just one fcs devices. Then we tried:

rmdev -dl dac1

but it didn't work ok, device busy. We tryied some combinations of rmdev commands without success, even varyoff anf exportvg VGs (that shouldn't be since it's suppose RDAC is a Fault Recovery solution) and finally rebooted the servers.

I have done this kind of change with SDD and Powerpath without problems. What we did wrong ??

Thanks in advanced

[ross.mather]

OK what I'd try would be once you've set one set of LUNS to use the primary path via the one Fibre Card - is to block the zoning for the other port in the SAN Switch.

That way you should be able to remove stuff as it can no longer be seen by the second path - don't you love automatic error recovery?

If that doesn't work then I'm at a loss as to what to do next!

[cdelgadop]

Hi Ross, thanks for your answer.

What i really want to test is the procedure to change a faulty HBA using the fault recovery features of RDAC. We are working in the configuration of several VIOS and want to bullet proof all the design and we are using DS4500. Other solution we are thinking about is to use our new SVC to virtualize all storage and install SDD instead of RDAC in VIOS.

Anyway, i'm still testing RDAC.