SAN Migration and Linux Storage Device issues
The scenario is the following:
– SAN migration from an old EMC Clariion CX-500 to a new CX3-40
– 2 Linux RedHat 3.0 AS and Oracle RAC 9.2 with OCFS 1.x
The goal is to migrate all the Oracle Data partition (1 LUN in this case) to the new SAN using EMC SAN Copy.
All the host will be powered off (yes we can live with this…).
The main issues are the following:
– PowerPath will mess up the device naming. If your device on the old SAN was seen as /dev/emcpowera, when you connect the hosts to the new SAN it will probably see the LUN as /dev/emcpowerb. To correct this problem the trick is the following:
- Stop PowerPath
- cd /etc
- mkdir /etc/EMC_BACKUP
- /bin/mv emcp_devicesDB.dat emcp_deviceDB.idx powermt.custom /etc/EMC_BACKUP
- Restart PowerPath (this will recreate the files you have moved above)
- powermt config
- powermt check
- powermt display dev=all (here you should see your LUN again as /dev/emcpowera)
A really strange issue that happened to us, is that we have to force the link speed on the new 4Gbps FC switch to 2Gbps, otherwise the lpfc Linux Driver was unable to correctly detect all the I/O devices (the HBAs are quite old Emulex LP9002). May be that some lpfc_* parameter to the module was missing, but there wasn’t the time to investigate further (and documentation about this is lacking IMVHO…).