I have a dell poweredge 840 with the SAS5/IR hardware Raid controller. I would like to install ubuntu server on this machine but would like to know more about the drive partitioning.

Even though the Raid controller is hardware based do I still need to partition the drives treating them as a software raid. I've called dell twice and got two different answers and I’m not sure how to continue. Isn't a software raid partition used when multiple hard drives are used as one even though the bios sees them as individuals? In my case during install I only see one drive just the size increase.

What are your thoughts, I’ve installed the system without the software raid partitioning and have tested a hot swap and it works fine, but I don’t want to run it this way if it compromises anything.

Thanks,
Rob

You're right: software raid can be used when you have multiple drives (or even a single one, though it's mostly useless, unless to plan to add a new one afterward).
If you're installation just saw a single drive, then it means that the hardware raid controller is seen by the kernel as such, and using software raid would be useless. As well, if you managed to hot-swap a disk without downtime, then it means that the hardware raid controller did its job, and you should be fine.
However, I would worry about the raid controller set-up, and also how about being notified when something goes wrong. Is there any integration of your controller in linux (e.g. via SMART) that allows for such monitoring ?

Note:
The advantage of software raid over hardware raid is that it's mostly hardware agnostic, but it's usually slower than hardware raid.
Hardware raid is faster, but you have to incur the cost of the controller, and if the controller is toast, then you have to find exactly the same one if you want your data back.

If you have Hardware RAID, use it. It has advantages over Software RAID. And no, if you're using HW RAID, why would you then create a Software RAID with the disks?

Some of the advantages to using Hardware over Software:

All of the overhead is on the controller. Usually the hardware controller will handle all the cache for read/writes, etc. Software RAID has to use the CPU(s) within the OS and machine, taking resources away from the OS and Applications running, etc. Also battery controlled Hardware controller can result in no data loss if there's a power loss during a write to disks, etc.

Hardware also implements hot swappable drives. With Software, you have to shutdown the OS, replace drive, restart OS.

Also with Hardware based, you can utilize to have your /boot partition on multiple drives. In a usual software RAID setup, you only have /boot on it's own partition on one drive, while the remaining OS is in the RAID array. This makes it easier if one drive fails, the system will still boot on one of the other disks still intact, etc.

In my exprience, I've never had Hardware fail me. Software has given me plenty of headaches.

Go and stick with Hardware if you have it already and don't worry about Software unless you have to deal with it.

That's not completely true. You can still get your data back (just more work), you most likely just can't plop in a new controller and expect the same setup if you do happen to have a controller no longer being made or sold, etc.

Thanks Everyone

Robert