RHEL 4 AS - EMC SAN configuration question

[Leibniz]

I posted this in the storage area if ITRC but go 0 replies after 4 weeks - so I'm posting again here in hopes that someone can help me with a continued problem that we have.

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Hi: I have a SAN question that I hope someone can answer.

Background:
I've been doing Linux admin for a long time, but my experience with SAN is fairly limited.

Situation:
We have an HP BL460 with RHEL 4 AS, and EMC SAN. The server is currently configured properly and running fine. It has 8 LUNS and redundant adapter configuration with PowerPath.
Currently there is no problems.

Plan:
The plan is to move the data onto new LUNs, because apparently the current LUNs that we are using are not on the right frame for SRDF replication.

So, currently I see 8 LUNS on two devices, and all looks well.

Problem: The new SAN (8 LUNS) has been presented to the server, and I see them. However, I only see them on one adapter.

The output of /sbin/fdisk -l shows 10 extra devices on /dev/sd? when the first 16 (sda - sdp) are negated since they are part of the current running config)

So my question again is: should I see 8 LUNS on *both* adapters before it is PowerPath configured? and should new my /dev/sd? devices be the same number as the new number of LUNS I see?

I am assuming that I can't properly configure PowerPath when I only see the new devices through one adapter. Correct? Or not?

Thanks for reading.
Bill

[Steven E. Protter]

Shalom,

If you have a direct fiber connection you need to get the world wide name of the fiber channel adapters, and program it into the EMC LUN, which needs to present the LUN to the Linux system.

Linux has multipath built into the OS and what you probably have here is to paths to each LUN.

SEP

[Leibniz]

Thanks for the reply.

My question, however, is still unanswered.

Please correct my faulty assumptions here, but at this point, this is my assessment of my situation.

If the WWN numbers of the Qlogic fibre adapters (read: both adapters) is properly configured on the EMC side, should I not then see the SAN from BOTH adapters?

I am assuming that our EMC admin has not correctly configured the SAN, because I can not see the SAN from both adapters.

More specifically, the second adapter is the one through which I can not see the SAN. Therefore the WWN number of that second adapter may not correctly configured on the ENC side.

Yes/No/faulty logic?

Thanks

[Ivan Ferreira · Accepted solution]

>>> So my question again is: should I see 8 LUNS on *both* adapters before it is PowerPath configured?

Yes, you should see 8 LUNs on each adapter. Suddenly, I don't know about PowerPath.

>>> And should new my /dev/sd? devices be the same number as the new number of LUNS I see?

This depends! If the multipath software already configured the devices, probably you will see only one /dev/sd? for both paths. This is the case of qlogic failover enabled driver.

>>> I am assuming that I can't properly configure PowerPath when I only see the new devices through one adapter. Correct? Or not?

Try with SAN Surfer, you can identify the devices seen by each HBA with that utility. You can then confirm if you have a problem with the LUN presentation/access or only with device special files creation.