emc on RHEL

[brian_31]

We are running PowerPath on RHEL4/5 servers, I am trying to understand the standard troubleshooting process incase we have issues. we had once such case where RAC 2 node cluster with the oracle rac filesystems on emc. The problem seem to be there was only one path on one node. after several reboots the issue the fixed and the system would boot up if the fstab entries were commented. in such scenarios what should we look for? i have mentioned some steps below pl add more to this..

lsmod|grep emc (to see if emc modules are loaded)
Can PowerPath see devices?

#powermt display dev=all

if not run

powermt config

most of the time we get errors where only one path is available, what should we do in this case. please add relevant answers.

Thanks

Brian.

[Matti_Kurkela · Accepted solution]

Knowing the model of your EMC storage equipment would be rather important in this case.

Anyway, EMC publishes "Connectivity Guide" documents, which include all the necessary HBA firmware version levels, SAN-side configuration options and sometimes OS configuration tasks required to make the SAN work. These documents are available at powerlink.emc.com (registration and EMC product serial number required).

The first check at the Linux side would be to check the HBA status in /proc/scsi/*, /sys/class/fc_host/host*/* or /sys/class/scsi_host/host*/* (depending on the Linux version and HBA manufacturer) and verify both HBAs are online and connected to the SAN.

Then get the latest Connectivity Guide for Linux (or ask your SAN admin to get it for you), and double-check all the settings listed within for your Linux version and storage model.

The next step would be to verify SAN-side zoning and masking configuration. If the storage is configured to show the disk to one HBA only, it's no wonder you are seeing just one path.

In a fabric SAN, the zoning configuration is important too: for example, in a EMC Symmetrix storage system, each Symmetrix director has its own LUN masking settings. If the fabric zoning does not allow the server HBA to access those particular director port that has the masking settings for that HBA, the path will fail.

MK