Hi all:

Looking for feedback as to upgrading EL3 to EL4.
Can this be done via up2date?

I also have an EMC Clariion attached to this system. What will I need to be aware of when doing the upgrade so I can reattach to the same LUNs?

Thanks for the help!

Upgrading the OS via the up2date process is not a good idea when moving from a 2.4 to a 2.6 kernel (to many changes for the this to work correctly). The RHEL 4 media (CD/DVD) is a better idea, as with every major OS upgrade it is a good idea to make and test a backup before starting.

As far as the EMC Clariion goes, it would a be good idea to contact them before starting the upgrade, they should have the information you need.

Lenard is right. Upgrading OS in situ even if possible is usually a waste of time because:
1) No matter how much pre-testing you do you usually find things you missed.
2) The upgrade invariably leaves a lot of garbage that was only relevant to the prior OS version on the server. You never are sure what is safe to delete so usually keep it around "just in case".
3) Other than pure OS stuff there are usually other issues you can clean up by doing a fresh install (users that have gone away, apps no longer used, etc...)

Doing a fresh install lets you know that what is on the system is what you want.

Of course before doing one you want to make sure you've checked compatibility for any apps you're using. They may work just fine in the old version but not in the new though typically there is backward compatibility within the OS itself. You may find vendors saying it's "not supported" which not the same as saying it won't work. They are saying if you have issues you're on your own. Often where you have multiple apps you'll opt to do something even if it's "not supported" by one vendor because it allows you to move forward on something else.

As he said make a backup of what you do have. Also insure you still have the old install media so you can revert if necessary.

If your Clariion is SAN attached you have to check out the LUNs it has configured for the host and how they are zoned to the host (via Connectrix perhaps?). You can see if you ecc and/or Navisphere on the host to explore what it has.

A Navisphere command line (navicli) that would give you all the WWNs for LUNs on the Clariion would be:

navicli -h <ipaddr> getlun | egrep "Megabytes|Name |RAIDG|UID:" | awk '/Name/ {printf $2" "$3" \t"} /RAID/ {printf $3"\t"} /LUN Capacity/ {printf $3"\t"} /UID/ {print $2}' | sort -n -k 2

Where <ipaddr> is the IP address of your Clariion's SPA or SPB.

Note the above command shows all LUNs in the Clariion - not just the ones assigned to the server. You'd have to determin by looking at the Navisphere itself which LUNs are assigned to your server.

Typically typing the IP address of the SPA or SPB in a Web Browser will pull up the Navisphere interface. You can see assigned hosts etc... using that.