Find out RAID level on HP DL360 server

This is several questions in one, so I'll try to address a few of them.

I typically set Smart Array controllers to leverage a higher write cache ratio. I prefer to have 75% write cache because the OS (using the XFS filesystem) caches aggressively. XFS will make a difference, but what are you tuning for? Are you tuning to simply achieve specific numbers, or is there an application requirement driving this?

ext3 isn't the fastest filesystem out there. But you have some mount options (e.g. noatime) and journal settings you could tweak.
I don't use LVM, especially with HP controllers that can provide many of the same benefits.
You have I/O scheduler and elevator settings (e.g. noop or deadline, in this case) that can be tuned, but that's a function of your application's actual needs.

If you do go with XFS, try a basic config then try some advanced configuration settings. Over time, I've ended up with mount parameters very similar to the one in the original link.

I just ran the following iozone command line on an XFS partition contained within a DL380 G5 with P400i, 12GB RAM and 8 x 146GB 10k drives. The elevator is set to deadline:

Command line used: iozone -t1 -i0 -i1 -i2 -r1m -s24g

initial writers  =  348957.75 KB/sec
rewriters        =  335130.03 KB/sec
readers          =  132851.70 KB/sec
re-readers       =  137116.27 KB/sec
random readers   =   35774.41 KB/sec
random writers   =  250618.38 KB/sec

Some of those systems should have onboard controllers, no? The G5 models may have PCIe cards (Smart Array P400 is most common), but the G6 systems should have Smart Array P410 models embedded on the motherboard.

You're dealing with two generations of system, though. The G5's have different drive bay and controller connections than the G6 systems, so I would not lump the DL360 G5 and DL360 G6 together. The G5 ProLiants have SAS SFF-8484 connectors internally. The G6 ProLiant systems have SAS SFF-8087 connectors internally.

They are vastly different systems. Can you provide the specific controller model installed in the DL380 G5, and what spare parts you have available?

Edit: I'm assuming you have a Smart Array E200 controller in the DL380 G5. That controller does not support RAID 5 unless you add a Battery-Backed Cache unit (BBWC - #351580-B21) to the controller. Without going into the issues with deploying RAID 5, that part is all you need in order to make the DL380 G5 do what you want. If your G5 DL360 has a P400 or P800 controller available in PCIe form, you can move that over to the DL380.