As promised, we tested the new 6Gb/s SSDs in the 2010 Mac Pro. We were able to test both the OWC Mercury Extreme Pro 6G SSD and the OCZ Vertex 3 SATA III SSD. The factory drive sleds give access to the built-in 3Gb/s SATA controller, but to get the full speed of the new 6Gb/s Solid State Drives, you need a 6Gb/s PCIe 2.0 host adapter. We tested two: the ATTO ExpressSAS R644 and the HighPoint RocketRAID 2721. Both 8 lane adapters have two mini-SAS ports (one internal SFF-8087 and one external SFF-8088). Each mini-SAS port supports up to 4 drives.
In this session, we tested single drives on both the internal and external mini-SAS ports. The goal is show that you can get the same 500+MB/s performance from 6Gb/s SSDs in the Mac Pro 2008-2010 as you can with the 2011 MacBook Pro with 6Gb/s internal connection. We will explain below what pieces and parts are required.
The first two graphs show the results for the DiglloydTools DiskTester Sequential test (2G test size, 5 iterations). It's a great simulator for large sustained transfers like those performed by professional video and audio creators. Longest bar (RED) means FASTEST.
NOTE: The crazy fast small random read speed of the ATTO R644 is explained by them as "secret sauce." It appears to be a caching scheme.
LEGEND
OCZ 240G (H) = OCZ Vertex 3 SATA III 240GB 6Gb/s SSD connected to the RocketRAID 2721
OWC 240G (H) = OWC Mercury Extreme Pro 240GB 6Gb/s SSD connected to the RocketRAID 2721
OCZ 240G (A) = OCZ Vertex 3 SATA III 240GB 6Gb/s SSD connected to the ExpressSAS R644
OWC 240G (A) = OWC Mercury Extreme Pro 240GB 6Gb/s SSD connected to the ExpressSAS R644
OWC 120G (M) = OWC Mercury Extreme Pro 120GB 6Gb/s SSD inside a 2011 MacBook Pro
OCZ 240G (i) = OCZ Vertex 3 SATA III 240GB 6Gb/s SSD using the Mac Pro's built-in 3Gb/s port
Veloci600 = WD Velociraptor 10K 600GB HDD using the Mac Pro's built-in 3Gb/s port
ANALYSIS
If you use the built-in 3Gb/s Mac Pro SATA ports, the 6Gb/s (SATA III) SSD will perform no better than a 3Gb/s SSD. But you can squeeze out the full potential performance from 6Gb/s SSDs like those from OWC and OCZ if you employ a 6Gb/s PCIe 2.0 host adapter. Notice the HighPoint card is fastest for large sequential reads while the ATTO card is fastest for large sequential writes.
The crazy fast average small random read speed of the ATTO R644 is explained by them as "secret sauce." It appears to be a caching scheme. On the other hand, the average small random writes were sub par due to very slow 4K to 64K transfers.
"COME ON MAN!"
I would like to see better support for 6Gb/s storage from Apple. It would be nice if the next edition of the Mac Pro whose built-in controller supported 6Gb/s drives. And for existing Mac Pros, Apple should offer a 6Gb/s PCIe 2.0 RAID adapter that supports SAS and SATA SSDs mounted internally. (The existing Apple Pro RAID card does not support SSDs of any kind.) Until those wishes come true, the power user is left to seeking third party solutions like the ATTO and HighPoint host adapters.
CAN YOU BOOT OS X?
ATTO's R644 will boot OS X if you flash it with the efi64 flash update file from the Mac OS X Flash Bundle. After using Carbon Copy Cloner to clone our OS X boot drive to a triple SSD RAID set, we confirmed that the R644 does boot OS X. The HighPoint RR2721 (and 2722) does not have an EFI BIOS so it can NOT boot OS X. (That is confirmed as true.)
If you are planning to boot from a RAID 0 array, you may not see any better performance than you would booting from a single SSD. That's RAID set can't do any more transactions per second than a single SSD. And the random small transfer rates are only slightly higher with two versus one. And three or four were no faster than two. The main reason for booting from a multiple 6Gb/s SSD RAID set would be for the extra storage capacity. You might consider booting from one 6Gb/s SSD and using a striped set of three or four to use as a scratch volume or working capture/playback volume.
DO THE CARDS MAKE THE MAC PRO NOISY?
The host adapters have heatsinks without fans, but ATTO overrides the Mac Pro's system fan management with their own fan speed controller. Problem is that it runs up the fans to full speed at all times regardless of the temperatures. We chose to remove it. We monitored temps and controlled fan speeds with smcFanControl. (Max PCI bay temp should not exceed 60C or 140F.) In our testing, the temps never came close to the max and we never had to tweak the fan speeds.
DETAILS: Host Adapters
We chose the ATTO ExpressSAS R644 and the HighPoint RocketRAID 2721 because both are 6Gb/s rated. Both have an internal mini-SAS port as well as an external mini-SAS port. Both are designed to support four internal drives and four external drives (in an enclosure). Both are 8 lane PCie 2.0 host adapters that support both SATA and SAS drives.
Officially, HighPoint only supports host adapters with external ports (RR2722 and RR2744) on the Mac Pro. As you can see from our test results, the RR2721 works fine on the Mac Pro using the RR2722 drivers. However, when one reader had a problem with the RR2721, he could not get any support from HighPoint. Though the ATTO ExpressSAS R644 costs significantly more than the HighPoint RocketRAID 2721 and 2722, it does boot OS X. Secondly, it gives you more setup and performance tweaking options for your RAID set. Thirdly, ATTO fully supports host adapters for the Mac Pro with internal ports.
Speaking of price, don't get seduced by the low cost single lane (x1) 6Gb/s host adapters. They may be adequate for HDDs, but SSDs will be hamstrung by the lower bandwidth. For example, our tests with a dual port x1 6Gb/s host adapter showed a maximum of 392MB/s READ speed and 220MB/s WRITE speed with two 6GB/s SSDs in a RAID 0 set. Compare that to the 1005MB/s READ speed and 949MB/s WRITE speed we saw with dual 6GB/s SSDs using the eight lane (x8) host adapters.
DETAILS: Enclosures
If you want to run the 6Gb/s SSDs externally, ideally you'll want a 6Gb/s rated enclosure or one with a "dumb straight-through" backplane. We have tested the 6Gb/s SSDs with the Stardom/Raidon ST8-U5 and the FirmTek SeriTek/2eEN4 enclosure. Both get the full speed out of the 6G SSDs. The easiest way to install an SSD in one of these enclosures is to convert it to 3.5 inch form factor with mounting holes. We used the Icy Docks sold by OWC. The newest silver metal Icy Dock works fine in the FirmTek two and four bay enclosures but the Stardom/Raidon ST8-U5 required the black plastic Icy Dock due to the fact that the newer metal version has a ridge in the back that keeps it from plugging into the ST8-U5 backplane.
DETAILS: Internal mounting options
If you want the 6Gb/s SSDs mounted internally to the Mac Pro and connected to the third party 6Gb/s host adapter, the installation is a bit more tricky. Placing the SSD inside an Icy Dock makes it easy to attach to any drive bay sled, but you'll need a custom sled that bypasses the data connector on the Mac Pro's backplane. We have successfully used two options. MaxUpgrades offers a "Backplane Attachment" kit which enables the SSD to pull power off the Mac Pro's motherboard while facing the data port down at a 90 degree angle to enable connection with the host adapter.
Another custom sled comes with the Trans International "Pro Cable - 1 Kit" which turns the SSD 180 degrees so the data and power connectors face outward. Again, the idea is to bypass the built-in data connection and connect to the 6Gg/s PCIe host adapter. This kit also provides power cables.
DETAILS: Cables
Finally, you will need to provide a data connection between the 6Gb/s SSD and the 6Gb/s host adapter. Since both the ATTO and HighPoint adapters use a mini-SAS connector externally and internally, you'll need a cable with the appropriate connector(s). We connected the ST8-U5 enclosure to the host adapter using a mini-SAS to mini-SAS cable (SF-8088 to SF-8088). For the FirmTek SeriTek/2eEN4 enclosure, we used a mini-SAS (SF-8088) to four eSATA fan out adapter cable. For the internal setup, we used a mini-SAS (SF-8087) to four SATA fan out adapter cable like this one sold on NewEgg.
WHAT ABOUT MULTIPLE 6G SSDs IN RAID SETS?
On April 29th, we posted results for RAID 0 sets of two, three, and four 6G SSDs.
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