RAID Roundup Revisited — Expansion Options
By Ned Soltz
There is yet another stage beyond a stand-alone 8-drive behemoth such as the Sonnet device. A number of vendors, Sonnet and Dulce included, offer expansion chassis which, in conjunction with their respective controller cards, support this expansion capability.
The HighPoint 4322 is my choice of RAID controller cards. It's dedicated Intel processor is faster than the prior generation; it is expandable with a battery backup daughter card; it supports both eSata and SAS drives through miniSAS 4-channel connectors; it's expansion chassis ready. My tests have already shown that the 4322 is faster than the 3xxx series. And at a price of $599, there is simply nothing elseon the market that comes close to its price/performance benefits. The 4322 supports up to 128 drives using expansion chassis such as the AIC.
I'm testing a 16-drive chassis from AIC, the XJ1100 (seen above), which retails around $1,600. It's a sturdy chassis with pop-out swappable drive trays requiring screws to secure the drive to the tray. Unlike many enclosures I've seen or tested, the drives trays are not lockable. I honestly do not see this as an issue; it might be of concern in a facility where a number of individuals have access to the units and there is concern of unauthorized removal of drives.
The AIC unit is effectively two 8-drive devices connected internally by an expansion circuitry. Four miniSAS connectors on the rear allow dual connections to the controller card and dual connections to other 16-drive expansion chassis. Chaining multiple enclosures together can create some significant storage with blazing speed!
Like any enclosure of this class, the XJ100 contains heavy-duty fans — three of them in fact. Heat is, after all, any hard drive's greatest enemy. If you are using this enclosure for editing, you will definitely want to locate it in another room or within a soundproof enclosure. It sounds like a wind tunnel. MiniSAS cables of up to 15 meters, though, can create more than sufficient distance between an edit station and a server room. In justfication, however, all large enclosures such as this are noisy as they really are designed to be servers.
The Seagate Cheetah drives came pre-initialized as a RAID 6 and formatted to a little over 6TB. RAID 5 is adequate for an individual workstation inasmuch as the odds of a dual failure of drives of this level of reliability and MTBF ratings would be rather slim. If configured in a SAN environment, though, I would certainly consider the added reliability of RAID 6. I chose not to re-initialize to RAID 5, knowing that RAID 6 would be slower. I wanted to see if there was any material effect of potentially slower throughput. As you will see shortly, these drives just smoke. No throughput worries here.
Note that 15K SAS drives are not available in the capacities of eSata drives, but the advantages are significant. The SAS drives are built for 24/7 heavy use with 1.6 million hours MTBF. Seagate designs them with specific error-checking algorithms. They are dual-ported, allowing the next drive in the array to take over immediately in the event of failure. For purposes of video, and this would apply specifically if the drives were being used in a SAN configuration, latency is a mere 2ms as opposed to a 4.1ms latency of eSata drives.
Because of this low latency and immediate response, EditShare only uses SAS drives in their turnkey SAN systems. I am certain this is the case for other vendors as well.
A faster rotational speed will naturally pump data faster and more reliably.
Take a look at the AJA System Test results for the Cheetah drives. Note as well that this speed is not just a function of the drives; the RocketRaid 4322 contributes significantly.
All I can say about results like that is WOW!
To test this in the real world, I copied to the drive several Red R3D files and exported 2K Quicktime files. I brought these into FCP, which transcodes the files to ProRes 422 HQ. These 23.98 fps clips played without a single glitch. I also transcoded to Blackmagic 2K 2048x1556 4:4:4 RGB.
All footage played without a hitch. Now something else: I was able to play these files in FCP with scopes open and updating in real time. Even on my 8-drive array, I will sometimes drop frames while playing back live scopes (seems to be a common FCP problem). I always suspected the culprit was drive speed and this array helped prove my point.
The simple conclusion here is that the Seagate 15K Cheetah drives optimal performance for any workstation or SAN configuration.
Seagate also supplied me with 16 1TB ES series eSata drives. These are the drives utilized in the shipping version of the Sonnet RAID reviewed here (except, as I noted, my test unit shipped with the much slower Hitachi drives).
When pricing drives on the Internet (which is, after all, what cost-conscious build your own RAID users will do), the ES (Enterprise Series) drives will cost more than the 7200.11 standard configuration. First note that the ES drives carry a 5-year warranty as opposed to the 3-year warranty of the standard drives. There are other features which set this series apart as well, including power-saving features and, most important for video, RV (Rotational Vibration Sensors). Let me explain.
When a number of drives are placed in an enclosure (and for this test, we’re placing 16 drives in one enclosure) those inertia forces from the spinning drives can cause vibration movement within the enclosure, sometimes causing an individual drive’s head to skip at random. Through a read-ahead cache, the RV sensors can maintain a constant uninterrupted stream of data regardless of vibration. Translated to video it means less risk of glitches and dropped frames. For that reason alone, do not consider a RAID (whether commercially marketed or DIY) that does not utilize Seagate ES drives. And one more thing, the ES drives boast a 1.2 million hour MTBF as opposed to 750,000 hour MTBF for standard drives. The statistic is valuable to the extent that it shows this is a better-built drive and well worth the rather minimal difference in price (less than 20%, street price).
Latency of the eSata drives will be something in the 4ms range as opposed to the 2ms latency of the SAS drives. I would have far less concern about greater latencies in a workstation drive than I would in a SAN configuration.
Now, for the real world. I installed the ES series drives in the AIC enclosure and using the RocketRaid browser-based GUI, initialized them as a RAID 5. This gave me something like 14TB of useable space. In the case of my test on a Mac, I used Disk Utility to create one large partition. Set up was quick and straightforward. Set up on a PC would be just as simple.
I applied the same AJA System Test parameters as for the other drives. As I would have expected, the 7200 RPM ES drives were about 10% slower than the 15K Cheetah array. But I’m not going to get bogged down here in drive statistics. What is more important is that these drives in the AIC enclosure driven by the RocketRaid 4322 provided more than ample speed for 2K, Uncompressed HD and ProRes HQ editing. Avid users would see sufficient speed to handle anything uncompressed or any data rate of DNxHD.
Who is the logical customer for this technology?
For the RocketRaid card, the answer is anyone wishing to create the fastest RAID with parity that relatively little money can buy. The 128-drive expansion capability makes the RocketRaid card an excellent choice for those with massive storage requirements. And that’s 128 drives with no degradation of throughput.
The XJ1100 is definitely an enclosure for someone who stores massive amounts of data and needs the luxuries of speed, capacity, and redundancy. And at under $1,600 for the enclosure alone, it represents an excellent value. As one documentary filmmaker friend who dropped by the studio as I was testing the unit said, "I'd fill this in a year." While I had some concerns about fan noise, that will be endemic to any similar enclosure.
The Seagate 15K Cheetah drives are suitable for highest-end work. Their speed and dependability makes them candidates for SAN applications, whether in this enclosure or in another system. Any user looking for the top performance in any hard drive regardless of the system, should strongly consider the Cheetah drives. Keep in mind that the 400GB 15K Cheetahs run in the $525 range.
But speed and data security? Priceless.
I have seen Seagate 1TB ES series drives on the internet as low as $160. Whether assembling a massive RAID or even just adding a single internal media drive to your computer, I wouldn’t recommend anything else.