There has been an increasing demand within the industry for media storage solutions with the flexibility to meet ever-changing high bandwidth environments. This quest applies not only to the larger production houses but also to the individuals whose editing needs go beyond the basic external hard drives. One alternative is the RAID which can provide both speed and redundancy.
Of course, deciding which RAID level to configure to is a matter of one’s preferences and needs. For those individuals and firms who may be new to RAID consideration, briefly, prior to reviewing the Accusys A08S-PS RAID, a small exploration regarding RAID levels and configuration is required.
RAID (Redundant Array of Independent Disks) permits multiple physical drives to be combined together so that all, or a segment of the array, is formed into a logical drive, which the operating system sees as a single storage device. You can configure a RAID in a variety of ways, but when deciding which level of raid to configure to, you must understand both the advantages and disadvantages for each level.
When a RAID is configured to a RAID 0, also known as a striped set, it splits the data evenly between the number of drives within the RAID enclosure. Though mixed sized drives can be used, storage space is limited to the capacity of the smallest drive. While speed and performance is increased due to the workload being balanced/striped between the drives, if a drive should fail there is no redundancy and, thus, all data in the array would be lost. In a way, a RAID 0 is not a RAID at all since it is not fault tolerant. A RAID 0 is best used for Read only and some gaming systems where integrity is not a critical factor. It is not recommended for any critical system, nor any files that you cannot reconstruct elsewhere.
A RAID 1 creates an exact mirror copy of data on two or more drives. This is especially useful when read and write performance are more critical, as opposed to the demand for more storage capacity. The RAID 1 does provide protection should a drive fail by copying over an exact copy of the data on the new replacement drive. Because a minimum two disc RAID 1 system is a mirrored image of the individual drive you are limited to only a 50% total capacity of the total drive sizes.
The RAID 5 uses a block level striping with parity data distributed across all disks and might well be the most popular RAID because of its low-cost of redundancy. You not only get redundancy, but more storage room for your media. A minimum of 3 discs are required for a RAID 5 configuration. While performance may suffer as compared to a single striped RAID, when the workload consists of several writes that are smaller than the capacity of a single stripe due to the necessity of parity needing to be updated on each write, larger writes can be done without a read-modify-write cycle for each data block by simply overwriting the parity block. As with a RAID 0, the capacity is set by the size of the smallest drive. The RAID 5 system is probably the best cost-effective option for providing both performance(especially so in ‘read’) and redundancy. Write performance is generally slower. The clusters and parity are evenly distributed across multiple hard drives and this provides better performance than using a single drive for parity. Parity information is redundancy information calculated from actual data values. If any single piece of data is lost, the remaining data the parity information can be used together to calculate the lost data. Parity information can either be stored on a separate, dedicated drive, or be mixed with the data across all the drives in the array. Out of an array with “N” number of drives, the total capacity is equal to the sum of “N-1 hard drives. For example, an array with 8 equal sized hard drives will have the combined capacity of 7 hard drives.
A level 6 RAID is similar to a RAID level 5. A second set of parity information is written across all the drives. This is equivalent to double mirroring. This level may be more fault tolerant than necessary, and while there is no penalty when in read mode there will be a drop in performance when writing. RAID 6 provides protection against data loss during an array rebuild, when a second drive is lost, a bad block read is encountered, or when a human operator. accidentally removes and replaces the wrong disk drive when attempting to replace a failed drive.
Often listed as a RAID 0+1, the RAID 10 needs a minimum of 4 disks. The upper layer mirrors the two striped sets below it, however, if one drive of each striped set fails, the data would be lost. Thus, one has to take into consideration the possibility of two drives failing at the same time. It doesn’t seem likely, but when you figure that the drives might well have been bought and installed at the same time, should one go down, there may be a good chance that another, being the same age and having the same usage, might well go down as well. It provides excellent redundancy, as the blocks of data are mirrored, and good performance since the blocks are striped as well. Stripe size is the maximum number of sectors the RAID system can access without accessing another disk. The stripe size is also the size of the cache for the RAID. A larger stripe is preferable since it reduces the number of I/O requests made to a physical disk and lets the buffer cache work more efficiently. There is a severely reduced amount of storage capacity amounting to only 50%. However, for critical applications, a RAID 10 may be the best option as it offers faster data read and writes and does not need to manage parity.
The Accusys A08S-PS RAID system comes with 8 hard drive bays so that eight 3 terabyte drives may be installed for a total capacity of 24 terabytes. It arrives with several power converter plugs for different countries, a PCIex4 cable, 2 rear panel keys, a quick start guide, screw pack, low profile bracket, a heavy-duty power cable and installation CD. It is manufactured with an Intel 10P341 800Mz processor and DDRlll memory and is capable of supporting RAID levels 0,1,5,6, and 0+1(10). The major components such as the controller, power supplies and fans are all modular in design allowing for easier and more convenient maintenance. In RAID 5 or 6 configurations, each drive becomes hot swappable so hard disks can be exchanged without having to shut down the computer.
The unit I received came solidly packed and protected in a large, heavy-cardboard box sturdily supported by thick styrofoam top and bottom insulators. It needs that protection as this is no light piece of equipment. The enclosure without drives weighs in at 24.5 pounds; with drives installed it feels more like 40 pounds, so you won’t be lugging this unit around from office to office very often. It is good-sized with a height of 1’ 8”, a length of 1’6” and a width of 11.5”.
In appearance, it is a perfect match for any Mac Pro user retaining the familiar perforated aluminum chassis; side by side, they look like kin. The unit I received contains 8 one terabyte drives spinning at 7200 rpm, which I configured as a RAID 5 providing me with a total capacity of 7 terabytes with redundancy should a drive ever fail.
Installation is fairly simply. Unlocking the rear panel and pulling it open reveals the 8 drive slots. Pressing a silver button next to each releases the handle allowing you to pull the disk tray out. A drive is then inserted into each of the bays sliding them forward until the connectors align with the end of the disc tray.
It is recommended that all hard drives should match in both size and speed and should be identical models with the same firmware versions. As previously mentioned, the smallest drive will determine the size of the array.
In use, the ACCUSYS RAID created some small start-up/shut down changes for me, which I quickly got used to. Normally, when finished for the day I would eject any externals, switch my monitor off, shut down the computer and walk away. With the ACCUSYS RAID you do not eject the mounted RAID from the desktop. You must first shut down the computer and wait until it is completely off. Then press the RAID’s on/off button to shut down the RAID. When starting up, the opposite actions are taken; you press the on/off button of the ACCUSYS and then turn on the computer. I discovered this after noticing that if I did not wait until my Mac Pro was completely down before turning off the RAID, my MXO2 box remained on for the entirety of the evening. For many who leave their computers on 24/7 this would not be an issue, but it is my habit to shut everything down for the night.
The ACCUSYS RAID powers on with a strong burst from the fan which lasts for a second or so. If all the drives are functioning as they should a line of green LEDs signifying the individual drives light up. Should one of the LEDs light as red, it means that the corresponding drive has failed or is having a serious issue. An amber light indicates a transition state such as a rebuild or migration and a blinking blue light indicates that disk access is occurring. If an LED shows no light, it means that no drive is installed in that bay.
Quickly after start-up the fan dies down, but there is a lower volume and consistent fan noise even in well ventilated areas that continues . While the noise is ever-present, I do not find it intrusive, and when testing out a new microphone, the fan sound did not come through my narration.
Even after hours of usage I can not detect any significant heat radiating from the RAID’s enclosure. It has been running all day as I write this and the enclosure is quite cool to the touch.
I conducted speed tests using both the old and new versions of the Black Magic Disk Speed Test as well as the Aja speed test. Each test was done multiple times on different days; the results are enough to blow you away and they certainly put any other drives I own to shame in both read and write modes. When I could, I selected the 5 gig stress testing option as it is the most technically accurate test and will average out any fluctuations in disk performance. The higher stress test value in the Black Magic Disk Speed test ensures that the test will not report artificially fast results due to the disk cache on conventional drives.
It is important, when conducting any speed tests to recognize that any drive will slow down to varying degrees as it is filled with media. The tests of the ACCUSYS A08S-PS RAID were done with only 572 gigs of media files copied over to it. Of the 7 of 8 terabytes of useable storage, I have barely begun to fill it.
Comparison tests were done on the boot drive of my 2 x 2.66GHz 6-Core Intel Xeon Mac Pro with 20 gigs ram, the Data Robotics DroboPro, an internal 500 gig drive and a G-tech FW 800 drive.
My current boot drive has a 1 TB capacity with 677.02 GB of available space.
I also conducted the Aja Speed Test with a 2 gig stress file, not shown, and saw only a very small increase in read and write speed. The Data Robotics DroboPro, with a total capacity of 16 terabytes, currently has 4.3 terabytes of drives spinning at 5400rpm. It is connected to the Mac Pro with an ethernet cable. Accounting for media redundancy, this leaves me with a total capacity of 2.97 TB, I have 1.39 TB of used space and 1.49 TB of free space.
Once again, for all 3 tests, there is a consistency in both read and write speeds between the three of them.
A 500 gig internal drive with 175 gigs of usable space available, and whose disc speed I do not recall, produced the below results below:
And for our final speed tests, a 750 gig G-Tech external drive with 243 gigs available:
It is abundantly clear that the ACCUSYS A08S-PS RAID is absolutely blazingly fast. Just for kicks, I used the Aja speed test to apply a 16 gig stress test and the results show a minimum reduction in the write mode and an actual slight increase in read speed.