HP Smart Array P420i Controller – Caveat: Need Flash Based Cache to Make Any Online Array Changes

We are in the process of setting up a Windows Server 2012 Hyper-V host with two server operating system guests, one DC and one RDS, and a couple of desktop operating system guests.

We were brought in to set up the environment at the hardware vendor’s request. So, this box was set up prior to our jumping in.

Since we do not work with HP servers on a regular basis we are not up on their terminology nor product features throughout their server lines.

We are in the process of looking into filling up the 2.5” hot swap drive bays as the server came configured with a RAID 10 (RAID 1+0) array and one global hot spare.

• HP Smart Array P420i Controller QuickSpecs Page

Having worked with Intel RAID Controllers most of the time as well as LSI RAID controllers we have come to expect advanced features to work out of the box. This is primarily due to the fact that we run with mainstream series or high performance series RAID controllers out of the box.

We avoid entry level if at all possible.

As we have discovered today, this is one reason why:

Note the following:

• Modular, easy-to-upgrade design lets you optimize performance by upgrading from 40-bit 512MB cache to 72-bit 1GB Flash Backed Write Cache or 72-bit 2GB Flash Backed Write Cache (FBWC).
• Addition of the flash backed cache upgrade enables array expansion, logical drive extension, RAID migration, and stripe size migration.

Obviously the emphasis is ours.

So, we are now in a position where we need to find out the cost on the 1GB and 2GB FBWC options for this particular server.

We are not sure what that cost will be but it will probably beat out our having to back up the entire server and its guests, that are already set up for production, and restoring the box using our ShadowProtect IT Edition license.

The clue that something was up came via the HP management utility that showed the following for the current RAID array configuration:

Note the distinct absence of RAID 6.

Apparently there is a license key that enables RAID 6 in this particular controller.

So, we hit two caveats with this setup:

• Flash based Cache is required for advanced RAID features.
• A license pack is required to enable RAID 6.

Ever try to purchase a base model car and add _just_ the features needed like cruise/tilt/air and a decent stereo and end up more expensive that the “LX” version of that vehicle?

It has been a disappointing trend in our industry to no longer be able to configure a Tier 1 server system, desktop system, or workstation system without having to knew the bits and pieces that these systems are made up of. We used to be able to configure systems that would just work as we expect them to and have the features we would expect for the price we paid.

Also, it has been our experience that the Tier 1 sales folks that _know_ these bits and pieces are very hard come-by with the onus being on us to make sure we have our ducks lined up _before_ we initiate contact.

Philip Elder
MPECS Inc.
Microsoft Small Business Specialists
Co-Author: SBS 2008 Blueprint Book

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