Which Distro for PPC64 Server?

We (work) have two IBM p505 Express Servers.

Right now one machine is running an old way out of support RHEL4 installation and the other is on Fedora 12, which is no longer supported by the Fedora Project. Paid support/subscription is not a consideration yet for this project, but I do want to run a modern Linux distribution for the associated modern application software and maintenance.

I basically need to move these servers to something free and supportable. I’m finding out that there aren’t a lot of options in PPC Linux as when I was last interested in this architecture. It’s pretty much just:

I realize there is RHEL and SuSE Enterprise for PPC64 but those are subscription products without free binaries available. I’m not prepared to build an RPM-based distro from source at this point so I need something with binaries or something where building from source is highly automated and integrated, such as Gentoo. Digression…

The question is which of these distros do I go with? To answer the question I suppose I need to define the roles.

These two pSeries servers a redundant pair running LDAP/Auth Service, NTP, DNS and DHCP. The load is low but I want a solid modern software platform on both these servers from now until they are replaced with in the future (which is likely to be integration into a centralized architecture).

With that said, and with my familiarity level of these distros, I would first lean towards Debian and then to Gentoo and finally to CRUX PPC.

Debian is a binary distribution, which is nice for maintaining a server. Debian is more familiar to me. What are the arguments for Gentoo or CRUX PPC?

Agree or Disagree?

Amber Lamps!

Amber lights actually, to be a bit more accurate.

We’ve got these two IBM p505 servers that actually work pretty well. They were purchased on some kind of clear out two-for-one deal that my predecessor jumped on and while I probably wouldn’t be the guy to buy these machines in the first place, I’ve come to strangely like them. These server run our DNS, DHCP and soon-to-be LDAP stuff. It’s all distributed, replicated and zone-transfered goodness.

However, as of this writing they are both sportin’ a solid amber light on the LightPath diagnostics and the procedure to clear the amber light is… well… rather unclear. I think it’s unclear because we don’t have an HMC (Hardware Management Console) so we don’t get a lot of the spiffy external management features that these systems offer. Add to the fact that we run Linux on these hosts as opposed to AIX, which apparently has OS-level tools for querying the event log and flipping the light switches. I can’t find anything equivalent on Linux for p-Series systems… yet.


Migration Weekend: Success

It was a long weekend of watching tape restores and restarting them as necessary but it’s finally over and everything appears to be mostly hunky dory!

I did discovery yet more small misconfigurations and strange behaviour along the way:

  1. OpenLDAP’s syncrepl using “refereshAndPersist” wasn’t working how I expected it to, no new changes were replicating to the slave LDAP server! I changed the directive to “refreshOnly” and set a 10 minute interval. I made several changes and monitored the slave LDAP server. Changes propagated in about 10 minutes, every time.
  2. Despite iSCSI’s maturity and the maturity of QLogic’s HBAs I still noticed strange, unexplained target drop outs. Two HBAs per server, two controllers in the IBM DS3300 and just one target out of four was dropping. At first, I couldn’t figure out how to properly reconnect the target on a live system so I rebooted. Later, I discovered you can “disable” and then “enable” the specific target in SANsurfer or iscli, which worked to bring back the dropped target on a live system. Multipath picked up the “new” path right away, as expected.
  3. Always remember to leave free physical extents in any LVM Volume Group in which you are taking snapshots of the Logical Volumes. It’s freakin’ obvious but I forgot and when I went to do snapshot backups, the snapshots were failing. Now I’m growing some LUNs on the DS3300 so that my VGs have room for snapshots.

All in all, a good weekend that was mostly filled with success.