External SATA RAID on a PowerMac G5
***I just put together and tested a SATA II PCIe RAID. Results here.
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I recently purchased a Hightpoint RocketRAID 1820A SATA adapter for my PowerMac G5 Desktop (2.0DP). The card is an 8-channel SATA adapter, operating at a max PCI-X bandwidth of 133 MHz. This page details my initial experiences with the card as well as some tests. Next week, I will be putting it through a series of tests in real world editing situations.
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| First off, my system is a G5 2.0DP (Fall '03 model) which is used for editing and video/film design. Before the additions, it had a BlackMagic Decklink Pro (66 MHz video capture card) in Slot 2 (100 MHz slot) and a UL4D (dual channel SCSI-320 133 MHz card) in Slot 4 (133 MHz slot). The UL4D is attached to an external array composed of 4 10k SCSI-160 75 GB Cheetahs. There is also 500 GB internal SATA, and 2.5 GB RAM. It is running OS X.36, Decklink 4.7 drivers, UL4d 3.20 drivers, RocketRAID 1.01 drivers. | |||||||||
| I purchased 4 250 GB Deskstars and the RocketRAID card from ZipZoomFly for $823.67 shipped. I also purchased a MacGurus "Roll Your Own SATA" 4-drive kit with 6-ft. cables for $281.86 for a total cost of $1,105.53 for 1 TB. Expansion to 2 TB would run another $900 approximately and would, at least in theory, increase speeds by utilizing all 8 channels. | |||||||||
| Installation: Installing the card was a little more complicated than usual, but not daunting. Because the Decklink card is 66 MHz, and the other two are 133 MHz, and Slots 2 and 3 on the G5 share a bus, I chose to put the RocketRAID in Slot 2, the UL4D in Slot 3 and the Decklink Pro in Slot 4. This throttles the RocketRAID and the UL4D at 100 MHz, but it is preferable to having one of them throttled at 66 MHz. Also, the card has internal connectors only, so I unscrewed the bezel from the card so I could run the cables out the back like this:
Putting the RAID case/drives together is the usual tedious business. Get a power screwdriver, it'll save you carpal-tunnel syndrome. There are great directions on the MacGurus site for using their kit. The card only comes with the Windows software, but the Mac OS X driver and control app are on the Highpoint site. |
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| TEST NOTE: All speed tests were done with BlackMagic Disk Speed Test, which writes and reads actual video frames (at various frame rates and resolutions). Unless noted, arrays were rebuilt right before tests. Reported value is the mean of 10 samples, with the highest and lowest discarded (I didn't figure out the standard deviations, but variance was very low). | |||||||||
Before getting to the SATA RAID, I wanted to see if moving the UL4D to a slower slot would have an effect on speeds. Surprisingly, the answer is "no". Speeds were off by <1% in both reads and writes. Perhaps this result would be different if the drives utilized both channels and were SCSI-320 drives. In any event:
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On to the SATA. The HighPoint control app seemed needlessly complex, and since I'm just doing a simple stripe, I figured I'd try out Apple Disk Utility RAID first, and lo and behold, it works great. Initial tests show speeds comparable to SCSI's.
Soon, I will be switching the SCSI array to a dual-channel setup, so this should change. |
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| One of the drawbacks with SATA is that as the drive fills up, the speed decreases. I found this to definitely be the case here as seen in this graph:
(I created a 100 GB video file and duplicated it as needed to fill up the array.) |
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| As you can see, writes really take a nose dive at the end. Still, even in the last 100 MB of the drive, speeds are fast enough for 10-bit SD uncompressed video, though I certainly wouldn't push it (read = 145 FPS 10-bit NTSC; write = 79 FPS 10-bit NTSC). | |||||||||
| In any event, I'm real happy so far. Will report back with further news as warrants. |
