What happens when the RAID volume approaches capacity? The speeds drop dramatically. Check out this graph at 90% capacity:

Legend:
MaXLine III = four Maxtor MaXLine III 300GB
Hitachi 7K250 = four Hitachi 7K250 250GB
Maxtor Plus 9 = four Maxtor DiamondMax Plus 9 160GB
Seagate 7200.7 = four Seagate Barracuda 7200.7 160GB

Observations:
1. The Maxtor MaXLine IIIs had faster WRITE speeds than the other brands and models of drive. However, the Seagate Barracuda 7200.7 exhibited faster READ speeds.

2. Notice that Western Digital WD2500JB drives are missing on the graph. We had to return the test units we borrowed before we could test them on the RocketRAID. However, based on tests done some months back on dual SeriTek/1S2s, we are confident they would have been the slowest of the pack.

TEST 2: ADD MORE THAN FOUR DRIVES
What if I put 5, 6, 7 or 8 of the fastest drives on the RocketRAID? How fast would it go? In this updated edition, we were able to stripe up to eight identical MaXLine III drives in a RAID 0 set using SoftRAID. QuickBench was out of the question when you consider that the total cache for 8 MaXLine IIIs is 128MB and QuickBench's largest block size is 100MB. So, again, we used DiskTeser but this time we used 5GB test file size.

In the last edition of these graphs, we observed what appeared to be a limit of 343MB/s for write speed. This time, with identical drives, we observed an amazing phenom. The six and seven drive RAID sets posted faster write speeds than the eight drive RAID set at 10% capacity. Very interesting. However, the eight drive set showed its stuff as we approached the capacity of the volume. At 90% capacity, it was 'pulling' harder than the six and seven drive sets.

As you can see, six good performing drives exceed the magic 180MB/s desired to process uncompressed 10bit HD video. And such a set exceeds that number even when the RAID volume approaches capacity.

One very nasty thing happened while we were testing the seven drive raid set. Three times in a row while running the 5 GB Disktester read/write test, our G5 had a grey screen kernel panic half way through the test. A few hours later, I read that an HD Video jockey in Texas had a kernel panic while duplicating a 5 GB file. We're still probing the limits of this card. If you plan to use this card for production, we want you to know all the problems we've encountered.

As you can see, the SeriTek solution would be as fast, but there's a downside. It takes up two slots on the G5 Power Mac. And to avoid bus contension, one of them has to be in slot 4 -- which many of you reserve for your DeckLink or Kona capture card. That's why the one card solution is most attractive.

Speed tests are sexy but let's review the features that are present or lacking in the RocketRAID:
FEATURES or advantages
You have room to grow with 8 ports
It captures 10 bit uncompressed HDTV with 4 or more drives in a RAID 0 set.
The included RAIDMan software supports RAID 0, 1, 5, 10 and JBOD.
It's compatible with both SSC and non-SSC drives.
The kit includes 8 SATA internal cables.
It runs on G4 and G5 Power Macs under OS X 10.2 or newer.
It's an affordable solution ($204 at ZipZoomFly)

'NON-FEATURES' or deficiencies
None of the 8 ports were external.
You can't boot your Mac from any drive connected to the RocketRAID.
There's no hot-swap support. You must Shutdown your Mac to connect/disconnect.
It does not support Deep Sleep
It 'hits the wall' at 340MB/s WRITE speed, with 5 or more drives in RAID 0 set.
Their RAIDMan utility runs slower than Apple's RAID software and SoftRAID and limits you to 2 terabytes.
It lacks support for G3 Power Macs with PCI slots
There's no support for Macs running OS 8, 9 or 10.1
The plastic connectors break easily. (This can be an issue especially if heavily shielded external use data cables are routed out an empty PCI slot to external SATA boxes.)
The included data cables are rated for internal use only. For external use, you should purchase cables with heavier shielding rated for external use and able to combat electronic interference that can compromise your data transfers.
Exhibits the disconcerting tendency to cause kernel panics under certain conditions.

CONCLUSION
The RocketRAID may not be the perfect SATA RAID solution, but right now it's the only game in town if you want one PCI-X SATA host adapter with more than 2 ports.

I have received email from readers running the RocketRAID who are ecstatic about the results. Others are not so happy. Two have reported various problems. You can read about one user's experience on the Apple Discussion pages. Both users reporting problems had crammed as many as 10 drives inside their G5. Their problems could be power related, since they are pulling power off either the SuperDrive or factory drives -- which may not provide the steady voltage needed.

Although the RocketRAID has only internal ports, I'm beginning to think that it will work best with the drives in an external box like the ones sold by MacGurus and Granite Digital.

HOW WELL DOES THE ROCKETRAID PERFORM ON A G4 POWER MAC?
We tested four MaXLine III drives (RAID 0 config) on a G4/1.42GHz MP Power Mac (64 bit 33MHz PCI slots). The sustained READ speed was about the same as the G5 (200+ MB/s). However, the sustained WRITE speed was an unimpressive 132MB/s (compared to 280+MB/s on the G5). Moral: If your project requires serious storage throughput, then it might be time to buy a G5 Power Mac.

MORE ON WHY YOU MAY WANT A SATA CONTROLLER WITH MORE THAN 2 PORTS
There are good reasons to have more than 2 ports on a your SATA PCI host adapter. If you have G5 Power Mac with a DeckLink or Kona card in slot 4 and want to control a fast SATA array for capturing 10 bit HD video or for Photoshop scratch, then you really need a single SATA host adapter with at least 4 ports. In spite of its 'non-features,' the RocketRAID is the only shipping Mac compatible SATA host adapter that fulfills that requirement.

Some of you have created a four drive, four channel SATA array using dual FirmTek SeriTek/1S2 cards. But you've also found that if you put them in slot 2 and 3 of your G5, the write speeds go way down. When you put them your G4 tower and span drives across the cards, the speeds go way down. If you are creating a RAID set with more than two drives, you really need a host adapter with more than 2 port/channels. Until someone else offers a four, six, or eight channel Serial ATA PCI-X host adapter, the RocketRAID is the only game in town for extreme Serial ATA RAID 0 sets.

Speaking of extreme, I received an email from a reader who is running eight drives on his RocketRAID and boots from the dual Raptors in the factory slots. Zowee! Mike Curtis filed a report on his website for independent filmakers on his 16 drive array involving the RocketRAID. He has plans for a 16 drive set once he replaces his defective second RocketRAID.