Troubleshooting SANs

I work for a consulting firm, and have begun to do troubleshooting on
small SANs, mostly HP MSA1500cs based.

Many times the problem the customer is talking about is some vague
intermittent slowness issue or something like that. In cases like
this, my troubleshooting goes something like this:

1. Check switch logs for marginal ports or other errors (usually
brocade 4/24s or similar)
2. Update to latest firmware and driver levels on HBAs, Switch, MSA,
etc.

If the problem still exists, I'll call HP support, but more often than
not they can't really help from here. So the only approach that
yields results is to start unplugging stuff until I see the problem
disappear.

In one recent instance, I had a customer start shutting blades off
until he found that one of them had an HBA that was mysteriously
causing the intermittent slowness for the whole SAN. The HBA actually
seemed to work, and there were no errors in the Windows event logs, or
switch logs, sansurfer, or anything.

There has got to be a better way to find this kind of thing. On an IP
network, I would run Ethereal or some other packet analyzer to try and
see what is talking on the network when the problem manifests. But
I've never really found anything like that for a fibre channel SAN.

As I said, I'm pretty new to SAN, so any direction would be helpful.

Thanks,
Sean