Which distribution should I use ?

The latest Debian Sarge (unstable, based on 2.4.25 kernel) image installed in about 15 minutes last night on a Poweredge 2600. I think the 2650 is the rackmount version of the 2600, so it should have nearly identical internal hardware.

You can get the beta3 install or the even newer "daily builds" ISOs at this URL:

http://www.debian.org/devel/debian-installer/

The only "quirks" were that upon reboot, the e1000 module wasn't loaded by default, so I had to add that myself to /etc/modules. Other than that, it went flawlessly. (The same 4/20/04 image on my home ICH5 system puked, so it may not be safe for ICH5-based Dell systems, e.g. Optiplex GX270 etc)

If you're using a system with more than one physical CPU, I don't think an SMP kernel is installed by default so you'd need to go through aptitude to change that. (Or recompile yourself)

This poweredge was configured with the hotplug SCSI hardware option based on a PERC4 controller I believe... as I only have experience (about 5 minutes worth) with the PE2600, I can't speak for the other hardware configurations you mention.

I haven't actually setup a hardware RAID yet, as I only have one drive module. I was planning on setting up a RAID in the next few days when I get some free time.

To actually answer your question, I think debian 'woody' may be too old to recognize the newer PERC SCSI controllers without an external driver disk.

I'm not very familiar with mandrake.

I've been running Red Hat Linux 8.0 (with all the updates, including the latest Fedora Legacy kernel) for quite a while on our Poweredges with no problem, but of course it was End-of-Life'd this year. We're getting 6 more PowerEdges delivered in the next week or two, so I'm going for Fedora Core 1 on those (probaby have 2 OS partitions, just in case Fedora Core 1 gives me grief - I prefer to cold install OS'es rather than upgrade).

I would say that Fedora Core 2 final, which is due out in about a month, might be too risky to put on a production server, mainly because of its use of the 2.6 kernel, which is arguably too new to have as much support as the 2.4 kernel has (e.g. does the Openmanage stuff work on the 2.6 kernel ?).

Well, I'm almost done deciding which OS'es to put on the 6 PowerEdges we got recently. Fedora Core 1 seems to be mostly a surprisingly poor choice for PowerEdge models - I say surprising because it's had 6 months of patches to mature with and yet seems to fail to install properly on way too many of those 6 models I tried. Fedora Core 2 Test 3 went on like a charm on most of the boxes (would have put it on the PE750, but I needed to get the machine quickly into service and couldn't wait for FC2 final to come out [which I can do with the other boxes]).

PE750: Red Hat Linux 8.0 - you need to download and build the latest Intel Gigabit Ethernet drivers though :-( Other than that, no problems. FC1 failed to complete installation.

PE4600: Red Hat Linux 8.0 - FC1 was a bust, plus FC2T3 or FC2 final might not let us install Oracle 9.2.0.4.0, so I played it safe here (we've installed Oracle 9 on 8.0 before without a problem).

PE2600s: Fedora Core 2 Test 3, to be wiped off next week with FC2 final - amazingly, a nice smooth install with all the hardware recognised properly and no stupid installer bomb outs which I got with FC1. Only worry is that Dell are dragging their heels with a 2.6 kernel-compatible version of their OMSA software (FC2 is out in days - where is an OMSA that works with it, Dell?!!), so we'll have to run the boxes without OMSA for a while until Dell deem that the 2.6 kernel actually is being used on production systems.