P222 or P420 controller?

[Cory Hug]

I'm looking at purchasing an ML310e Gen 8, but want to do RAID 5, using three 500 GB SATA drives in a hot plug chassis.  I know the disk controller built in to the base ML310e Gen 8 server does not support RAID 5, and so I need to upgrade the controller.

What's the difference between a P222 and P420, other than installed memory (512 MB vs. 1 GB) and the P222 has 4 internal and 4 external ports, and the P420 has 8 all internal ports?  I don't need the external ports on the P222, and I'd only need 4 internal ports anyway, so to save the money, I don't see why I can't go with it?

I can not find any other differences between the two in the documentation on each that I've read, and I don't understand what the benefit of the extra memory on the P420 would be.

About 2 years ago I built a similar server using an ML110 and a P410 controller with only 256 MB memory, so it seems the 512 MB memory on the P222 should be sufficient for my needs.  Unless there's some additional information I don't understand, in wich case I'd appreciate the details.

Thank you.

[Casper42]

The only difference aside from the ones you already mentioned is the P4xx family has more horsepower in the RAID engine inside the controller than the P2xx family.

Similarly the P8xx family has more horsepower than the P4xx.

But with only 3 drives and, I am assuming, 7200rpm on each, I think the P222 would be fine.

You can in theory upgrade the cache memory on any of the P series controllers as well. Right now you have 512MB / 1GB / 2GB options.

[Cory Hug]

Thanks much!  I would like to understand a bit more just for my own personal knowlede though, or to have an idea of how much room we might have to grow.  Yeah, I guess that's mostly was what I was wondering, what exactly does "more horsepower" mean?  Is it purely just the quantity, or maybe size (or some combination of both quantity and size) of drives it can support before you hit a performance degredation, or an outright physical limit where it just plain stops working?

Yes, the drives will be 7200 RPM, but can you give me more detail on why the rotation speed matters?

We might add a 4th drive some day, but I don't see us ever going beyond that (at least not before the server would be old enough to replace anyway).

And then I guess, is the only difference between the P2xx, P4xx, and P8xx the amount of memory they include by default?  If I upgrade a P222 to 1 GB cache, do I essentially have a P4xx just with the different internal/external port configuration?

It would be nice if the descriptions or spec sheets of these different controllers listed the maximum, or optimal, disk configurations supported.  Or is there some web page somewhere that will tell you which of the controllers you need based on inputs like # and size of disks?

Thanks again!

[Cory Hug]

I'm just about to finalize my config of my server, but I want to ask, is there no hardware RAID controller compatible with the ML310e Gen 8 servers thats even less expensive than the P222, but would still work for my purposes, as described in my first post?

In my older ML110, I used a P410 with 256 MB cache, which was about $400.  Even the P222 is still $600.

Is the P410 not compatible with the ML310e Gen 8 servers?  (If they even still sell the P410 now I suppose.)

I found a P212/256 (462834-B21) that's $379.  Is this compatible with the ML310e Gen 8 servers?  Do you think would work in my situation?  (Again, in the past I used a P410 with 256 MB cache).

I can't find any compatibility info anywhere.  Anywhere I see anything mention compatibility, all it does is direct me back to the main Smart Array Controllers page for "most current information" (http://h18006.www1.hp.com/products/servers/proliantstorage/arraycontrollers/index.html), where I can't find any actual compatibility info that doesn't just direct me right back to this same page.  It's like an infinite loop with no actual information.

Thank you again!