Monday, November 14, 2005

Turning Opteron Down

I was putting together a server spec recently. Nothing special, just a reliable box to store 100G or so of data safely and serve it up via the web.

Easy, right?

Well, that's what I thought, and I was wrong.

I have this thing about real servers. They have to have redundant PSUs, redundant disk - mirrored. This means greater than 2 internal drives.

(Note that, according to this definition, Sun's SF280R, V210, X2100, E220R, E420R, V480, V490, V20z, and E1280 don't qualify. All are limited by 2 internal drives. They're fine for compute nodes and similar tasks, where the aim is simply to survive long enough to finish the job and decommission the node, but not for real servers. You have to have at least 3 disks to guarantee survival - and reboot - after a disk goes. OK, so you're supposed to add external arrays, but usually you can't do anything like place metadevice databases on the arrays. And also, only having 2 drives make Live Upgrade harder than need be. End of first rant.)

OK, so the next thing is that 100G of storage. It doesn't really justify getting an external array - that's fine for a terabyte, but would be a waste in this case. And, unlike something like 10G you can't just lose it on the boot drives. So 100G is an interesting number.

Grabbing 100G off a SAN doesn't look promising either. Apart from not having one to hand right now, the cost of the HBAs makes a nonsense of it for this amount of data.

So, what else? iSCSI could be interesting, as it saves you the cost of the HBAs. But it's not really mature yet, and I don't happen to have a server handy. (I don't happen to have a convenient NFS server either, which is a shame.)

OK. So the next best thing is to get a box with 4 drives - 2 to house the OS and the application binaries, and a couple extra 146G drives for the data.

So, I start of by thinking - these Sun Opteron boxes look real nice. Particularly the X4100, which can take 4 drives without the DVD. (And you don't need a DVD - it's just something else to waste money and electricity.) However, this won't work. Sun only offer 36G or 73G drives. Not enough! And there isn't a slightly bigger variant that takes more drives. OK, so Sun don't make an Opteron box that will work. Bother.

So, go to Sparc. The V240 works a treat. I like the V240. A couple of boot drives and a couple extra 146G drives and I'm all set. It's interesting that an old Sparc box is better suited than a new Opteron box.

(Not that the V240 is perfect. In the same way that it's a major disappointment that the Opteron boxes don't take 146G drives, it's disappointing that the V240 doesn't support 300G drives. Why don't Sun realize that customers want choice?)

OK, so I'm a Solaris fan, and Solaris x86 runs on a wide range of systems. A quick browse through other manufacturers websites (and some of them are nowhere near as easy to navigate as they ought to be) shows that this trend of useless system design is fairly widespread. Other manufacturers are more agile at supporting larger drive capacities, but the systems designs are similar.

In the end I decided to simply park the problem in a zone on a bigger system. It's a good solution, and was what I wanted to do anyway.

What is intriguing is that Sun used to have ideal systems for this sort of task, and have now scrapped them. The V60x allowed you to have 3 drives, so you could avoid the twin-drive trap. The V65x was a wonderful compact server and let you put 6 drives in. The V250 let you put 8 drives in the chassis, but seemed to get canned pretty quickly. It's not entirely obvious to me that genuine progress is being made.


Peter Tribble said...

Menno Lageman asked me "How about the V40z?"

Fair question, and the V40z would meet the requirement. (As would a V880 or V890.) But it's pretty overspecified in other ways - it's big and power hungry.

I think this reinforces my point, in a way. You have to go a fair way up the range and get a fairly hefty machine just to get a fully redundant server for 100G of data.

(Although looking at the pricing for comparable configurations there isn't that much difference between a V40z and a V240.)

Solaris10 said...

There is a great deal of work been done in the X86 plataform. I am currently switching all my Windows Server 2003 into solaris, the OS seems to be very stable. In we shift gearsand refer to scalability, we have almost endless in solaris which is another thing I took at look at.

The new release of ZFS for Opensolaris just makes things super nice for this great OS. I hope ZFS is supported by default in the next release of solaris. Sun Microsystems rules.