Monday, January 31, 2011

Working with IBM Scaled x460's

IBM offers the ability to stack two or more x460's together to make the resources of all the servers (RAM, CPU, etc) available to the Primary server.  This is some pretty old hardware we're talking about here though, since then much better solutions have been developed.

But if you find yourself having to deal with one of these, here's some information I learned recently while troubleshooting this dinosaur of a machine:

1.       IBM says average cost to repair at this time is $2661. 
2.       These servers are not clustered (implies redundancy): they are scaled (implies increased performance capacity).
3.       When the two servers are properly working together, the state is called “merged.”  The primary OS will show the total RAM of both boxes, minus overhead. 
4.       When the two servers are not merged properly, the primary OS will show less than half the total RAM of the two boxes.  This is a good test for whether they are merged or not.
5.       When the secondary is merged properly, it will display a black screen to the effect of “This server is merged, please view primary server.”
6.       Each server has an independent BIOS.
7.       Both RSA’s should be available.  The RSA’s are also merged in some sense, I wasn’t able to look into this very much. 
8.       You obviously want to avoid powering down the Secondary before the Primary – this would be akin to yanking half the sticks of RAM out of a live machine.
9.       Removing the power supplies and putting them back in helps clear spurious errors and reset the machine.
10.    I recommend against ever touching, looking at, or thinking about this equipment.

To shut down these servers:
1.       Shutting down the Primary via the OS will automatically shut down the secondary.  Wait for them both to blink power lights.
2.       I have seen this hang before, at a blank grey screen.  If it does: manually power down the Primary, and then the Secondary. 

To start up these servers:
1.       There is a “latching” mechanism here:
a.       KVM the Secondary.
b.      Start up the Secondary first.
c.       When the Secondary says “Waiting for primary” at the blue IBM screen (1 minute or so), start up the Primary.  If you wait too long, the Secondary will give up and begin a “failure to boot” loop.
d.      The Primary will display a "initializing system memory, please wait" screen for several minutes.
e.      The Primary will then display “Initializing PCI devices.”
f.       The Primary will then display “Searching for Secondary server.”
                                                               i.      If it is not able to find the Secondary server, the Primary may automatically shut down.  If you start it again and it is still unable to find the Secondary, it will boot to the OS unmerged.
                                                             ii.      If you are attempting to get into the primary’s BIOS, press F1 shortly after the Primary displays that it was unable to merge.  It will acknowledge your input and boot to setup.
                                                            iii.      If it is able to find the Secondary, it will indicate its merging attempt was successful and then boot properly.

No comments:

Post a Comment