HD For Indies

I bought a dual 2.5 GHz G5 today almost on a lark - they had them in stock (only 2) at my local Apple Store (Barton Creek Square Mall in Austin, Texas), so I jumped at the chance and got me one.

I also received my 2nd (working) Highpoint RocketRAID 1820A card in the mail and laced up a horrible mess of cables.

I also happen to have 16 300GB drives sitting around the house. Bwahahahahaaaaaa....

If you haven't read my previous report (let's call it Frankentosh 1.0), scroll down to the article below to read it.

I tested with BlackMagic card in slot 4 (finally got a Mac it'll fit in Previously I couldn't get it to fit in my Dual 2.0 GHz G5 for fear of breaking something on the motherboard)

I put the 2 1820A cards in slots 2 & 3, and just lay the G5 on it's side and draped the cables over the top end of the computer, putting the clear airflow panel on the supine Mac and closing it as much as it would (not much). Drill/punch/cut time if I wanted to seal up the Mac.

The upshot -

Not a whole lot faster. My nomenclature:

X+Y+Z

where X=number of drives connected to the first 1820A connector
Y=# of drives on 2nd 1820a
Z= # of drives on internal SATA connectors (the "normal" ones)

I tried 7+7+2, got 481MB/sec reads, 424 MB/sec read/write
I tried 6+6+2, got 495.3/430.5 read/write (448/433 on last part of array)
6+6 was 439/380 read/write, 390/380 at the tail of the array
I tried 7+2 just to see if that did any better than 8+2, but was in slot 2 or 3, and got 500/425 read/write
In slot 4, 8+2 got 575/415 read/write

Lessons learned:

The card doesn't scale performance in a way that would be substantially useful for HD usage with an HD card installed.

With two cards installed, the RAIDman software that comes with the 1820A won't create a RAID bigger than 2TB. Dumb but true (they're working on it)

RAIDman can't span a RAID across two cards.

SoftRAID and Apple Disk Utility, while they cannot create RAID 10 or RAID 5 volumes, can create RAID 0 volumes that span cards (and can include internal SATA drives in the "standard" 2 internal SATA slots).

"Only" 430 MB/sec write speed seems to be the cap...but it holds it all the way to the end of the array, so clearly it's a card limitation, not a drive limitation. I was a bit bummed - with single SATA cards, my experience has been that drives achieve about 90% of the speed in an array (per drive) that they would by themselves. So In theory, this 16 drive array might have achieved 960 MB/sec.

I got read speeds a bit over half of that, but write speeds well below half of that.

This is all still RAID 0, so back up everything regularly to a stack of drives or else your are playing Russian Roulette with a LOT of bullets in the chambers. I'd expect an array of this size to fail every 3-12 months, just at a guess. Remember, 16 drives in an array makes the array 16 times more likely than a single drive to fail if you're only using RAID 0.

If you did suffer a crash, even with 50 MB/sec transfers, you'd be looking at over 25 hours to restore (after fixing) 4.37 TB in a fully populated RAID 0. This was for stunt purposes - nothing in HD res is going to nee that kind of throughput. If you needed this kind of capacity, break it into smaller logically sized/throughput capable units. But it is nice to know you could read & write 2K film scans (2048x1436 10 bit) in real time. Hmm, how much footage is that? About 4 hours and 42 minutes. Not bad!