Seagate Cheetah 15K.7
6Gb/s SAS Drive vs others
Posted Monday, November 2nd, 2009, by rob-ART morgan, mad scientist
Just when you think the drive makers have squeezed all the speed possible out of HDDs, they take it to another level. As you will see in the graphs below, we compared the new Seagate Cheetah 15K.7 SAS 6Gb/s HDD to the previous generation of 15K Cheetah SAS HDDs along with the 7K Barracuda ES.2 SAS HDDs.
These first two graphs show the results of the Area Test using DiskTester 2.0 (4GB test size, 256MB chunk, 5 iterations). We posted results for an "Empty" (0%) volume.
The second pair of graphs show the results of the AJA Kona System Test (4GB Test Size, 1920x1080 10-bit RGB Video Frame Size).
The graphs below show the average random transfer rate for small blocks ranging from 4K to 1M.
LEGEND of GRAPHS
15K.7 = Seagate Cheetah 15K.7 15,000rpm SAS drive (600GB)
15K.6 = Seagate Cheetah 15K.6 15,000rpm SAS drive (450GB)
ES.2 = Seagate Barracuda ES.2 7200rpm SAS drive (1TB)
Host adapter used: ATTO ExpressSAS H644 6GB/s
Enclosure used: Proavio EB8MS 8 bay SATA/SAS
Test software used: DiskTester 2.0, Kona System Test 6.0.1, and QuickBench 4.0.4
Test mule: Mac Pro Nehalem 2.93GHz octo-core (Snow Leopard 10.6.1)
We've come a long way from when you had to have six 7K SATA drives and four 15K SAS drives to capture uncompressed video. With the Cheetah 15K.7, you can easily do it with two -- even if the drives are full. The speed of one Cheetah now rivals the fastest SSDs in large sequential transfer speed, though the SSDs still beat it in random transfer speed and transactions per second. The Cheetah 15K.7 is the fastest SAS drive we've ever tested plus it now offers storage capacity up to 600GB.
Of course, the drives are pricey. And if speed is not the issue, there are 7K SATA drives with more than 3 times the capacity. Cheetahs are not meant to be all things to all users but for the tasks intended, they impress.
To squeeze the last drop of speed from the Cheetah, we chose a 6GB/s SAS host adapter: the ATTO ExpressSAS H644. This particular adapter gives you the flexibility of connecting to both internal and external drives (up to 4 each) using mini-SAS ports. And it also gives you the flexibility of both 3Gb/s and 6Gb/s drivers. We installed the 6Gb/s drivers for the 15K.6 and 15K.7 Cheetahs and the 3Gb/s drivers for the ES.2s.
As for mounting the test drives, we used the Proavio EB8MS enclosure which has 8 bays, dual mini-SAS connectors, and accepts both SATA and SAS drives. Though it is only rated at 3GB/s, no single drive we tested can attain that speed much less 6Gb/s. However, as soon as we get our hands on a 6Gb/s rated enclosure, we, of course, will re-run our tests to see if it makes any difference.
COMING NEXT: Test of the Seagate Barracuda XT 6Gb/s SATA drive connected to the new 6Gb/s Rocket 622.
WHERE TO BUY THE SEAGATE CHEETAH 15K.7 SAS HDD
Check the Seagate website for a list of sources. Some we found include Buy.com and MacSales.com.
WHERE TO BUY THE ATTO ExpressSAS H644 host adapter
Order from direct from the ATTO online store. Check also with MacSales.com.
WHERE TO BUY SPECIAL SLED KITS
(The Nehalem Mac Pro has been "crippled" so it only works with Apple's Pro RAID card. If you want to use a third party host adapter with internal SATA or SAS drives, you need a special sled kit that bypasses the backplane data ports. Contact the following companies for such kits.)