VMWare ESXi 5 - Expanded RAID 5 array - cannot access datastore

So there are a few issues to look at here...

RAID controller firmware is an most important item. You're referring to a Smart Array P400 controller, which would place your DL360 model as a G5 unit. One of the critical items involved in working with HP equipment is managing and maintaining firmware. Looking at the firmware revision history for that controller, there are substantial changes to functionality and feature sets between firmware revisions. So in general, upgrading firmware is something you should do regardless of this issue. The easiest wasy to accomplish this for your setup would be to download the HP Firmware DVD or the Service Pack for ProLiant DVD.

I probably haven't encountered this issue because most of the HP ProLiant G5 servers I've deployed used small-form-factor disks, so I didn't reach the capacities you're working with. Are you using HP-branded disks?

Since you're using ESXi, did you install the HP-specific version of ESXi? The HP build adds array and disk monitoring to the base package. Doing so allows the vSphere client to display Smart Array controller status. If you DO have this installed, see if the individual disks appear in the console under Configuration -> Health Status -> Storage.

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Finally, there seems to be a major issue with Smart Array P400 controllers and ESXi 5.0 (Issue #2006942). Under ESXi 5.0, the driver used in your controller can't see a logical drive greater than 2TB. HP now has two drivers available for its controllers. The cciss driver has been the long-standing driver in Linux (and VMWare), but has recently been displaced by the hpsa driver. The cciss driver does not support LUNs or logical drives greater than 2TB in the context of VMWare. The hpsa driver does. Unfortunately, the hpsa driver does not support your Smart Array P400 controller.

I don't think there's an easy solution for you. You've probably already expanded the single logical drive via the HP Array Configuration Utility. You cannot shrink HP logical drives. You may be out of luck. - I looked into ways to force the hpsa driver to load in VMWare, but again, it doesn't support your controller. - You could move the disks to a G6 or G7 server, which use Smart Array P410 controllers. - If you're adventurous, you could install a P410 controller in your G5 server and change SAS backplane cables. It's unsupported because it's an old server, but has an 85% chance of working. - If you're desperate, you could add another disk or two, create a logical drive with size < 2TB, boot into another OS/Live CD/GParted (maybe?) and use dd to clone the relevant partition to the new disk array.