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OWC ThunderBay 4: First Impressions


I recently began using the Other World Computing (OWC) ThunderBay 4 unit to add external RAID storage to my 2013 Mac Pro. As you may know, the 2013-2017 Mac Pro has limited internal storage due to its “innovative” design and the limitations presented by the computer bus itself (no second SSD possible). So, adding external Thunderbolt 2 storage is almost a requirement if you do anything interesting with your Mac Pro.

My ThunderBay 4 was acquired as a New-Demo unit and it came equipped with four (4) 3TB Toshiba drives and a SoftRAID software-RAID license. Because this chassis doesn’t include hardware RAID support, it’s a little more flexible and cost-effective than full-hardware-RAID versions.

The unit arrived quickly and came pre-configured with RAID 5, which allows the 12TB unit to have 9TB of usable space. I removed and reseated each drive and powered up the unit. While the Toshiba drives have a wide-range of online ratings and comments, I found them reasonably quiet, but the ThunderBay front panel had an occasional vibration that stopped when I touched it. The use of a self-adhesive pad to inhibit vibration would make sense there.

The SoftRAID product needs to be installed on your Mac, and there are trial versions on the website. I experimented with the Trial version while I waited for my delivery, and input the serial number from the ThunderBay 4 case sticker once that arrived. A new download then installed a ThunderBay-limited non-trial version of SoftRAID, and that will be fine for most people. I opted to upgrade to the full version, not ThunderBay-limited, and that was an additional US$99 for the upgrade, and involved an additional download and install.

I did a fair amount of research on different RAID levels because it had been some time since I considered which RAID level to use, and disk space has expanded significantly in that time. After a fair amount of reading (lots of opinions), I opted to reconfigure the TB4 as RAID 1+0, often quotes as the safest RAID if you worry about data loss. After running storage benchmarks using the Blackmagic Disk Speed Test, I decided that RAID 1+0 was not providing the performance levels I expected. Further reading pointed out that RAID 1+0 does not use a Write cache. My Write throughput was 350MBps, which was far below the advertised 550MBps of the hardware. At this point it was obvious I needed to go back to RAID 5. The advantages of more space (9TB versus 6TB) and better performance ( +40% ) more than offset the perceived risk of data loss in a power failure event. I am on UPS, anyway, and have seen the switch-over go flawlessly. What really impressed me was how little time it took to make the switch.

Switching from one RAID level to another means wiping out your data, usually. There are Conversions you can do, from RAID 0 to RAID 1+0, without data loss, but a switch from RAID 1+0 to RAID 5 wipes out your data. So you need to backup and restore your data. I used Carbon Copy Cloner (CCC) to do this to an ancient WD MyBook over Firewire 800 (using an Apple TB-FW adapter) and things went flawlessly. The RAID change itself took very little time, and the restore of the backup with CCC was flawless.

So, what do I think? As a person who has used Network Area Storage (Netgear ReadyNAS) and hardware-RAID for years, I’m impressed. I can launch large virtual machines from the TB4 and not feel like I’m waiting and waiting and waiting. The difference between a 20Gbps TB4 and a 1Gbps Ethernet connection is obvious, and you can certainly feel it. With Thunderbolt 3 emerging, you can imagine six-bay units are about to roll out, too.

Some math for Thunderbolt. Thunderbolt 1 was two (2) 10Gbps channels. Thunderbolt 2 combined those two channels into a single 20Gbps channel. Four (2) SATA drives, each of 6Gbps, would have theoretical throughput of 4×6 or 24Gbps, so having a 20Gbps interface to four drives makes a lot of sense.

SoftRAID payments are through OWC Holdings, so you can imagine there is some relationship there. I was disappointed to find the TB4-included license limited to ThunderBay units, but upgrading that limited license to a full license was a financial wash. I just think OWC should highlight that the included license is limited to better manage your expectations.

One side note: the SoftRAID “Certify” command is outstanding, and you should run this on any drive you intend to use for long-term storage. It will make two painfully slow passes through your disk writing random patterns to the storage and reading them back to make sure they are correct. Then a third-pass is written as zeroes. I have a 50% pass rate on the discks I have in my spares and I label them SoftRAID Certified and know to use the others as scratch temporary disks. Nice feature, but it can take days to do a large disk. Be patient.

I will provide updates as I gain more experience with the OWC ThunderBay 4 and SoftRAID, but it seems to “just work”. Pretty simple.


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