Bootable Mac Pro RAID

Posted by mitch on September 20, 2010

I do a lot of heavy disk I/O on my desktop Mac in testing code related to storage. For years I’ve wanted to have some fast primary storage on my Mac to speed up my work. In the past, I had used internal SATA drives and software RAID for drive failure protection, but speed isn’t really there. In hindsight, I probably should have ordered my Mac Pro with the built-in RAID card. The card runs around $800, but installing it apparently requires some cable work that I didn’t want to get bogged down in. After reading some of the forums, I wasn’t sure that was such a great choice for me either. I considered SSD for boot and some kind of cheap external RAID for data, but most of the cheap external FW RAIDs are crap (I tried a few of them).

What I ended up with has been fantastic. I have a 8×1 TB physical array with 7200 RPM SATA drives that run around $90/ea on Amazon. These are in a single 8-drive chassis from I had never ordered from these guys before, but the order showed up fast and in good shape. I bought two SAS cables and an internal SAS card–the Areca 1680x. Altogether, this ran me about $2,300 for the drives, chassis, and the SAS card and cables.

With the EFI firmware loaded into the Areca 1680x (found on their FTP site), the SAS card is bootable in my 2008 Mac Pro and I have no internal hard disks. The RAID is configured as a 7 disk RAID-6 with 1 spare drive. Creating the single RAID volume (~5 TB usable) took a while, and I/O performance is very fast.

Management for the Areca card can be handled with a local driver and web browser, or through Ethernet and a web browser, which is what I’m doing. The card provides a separate Ethernet port for management, so there’s no weird software bridging. This is awesome stuff–the PCIe card is essentially managed as an appliance via HTTP from any host.

On the left, Xbench results with a single 2 TB SATA drive.  On the right, the SAS-SATA RAID. (Click to view full-size.)

One thing to keep in mind if you are new to RAID–RAID is not a substitute for backups. A hardware RAID is formatted by the controller card and only that card will be able to read the data. For backing up, I use Time Machine with a Drobo Pro loaded with 12 TB of drives, connected via iSCSI on a dedicated NIC. This works very well; in fact, I installed my data onto this RAID by doing a recover from Time Machine.

If you’re looking for high-performance direct-attached storage for a Mac Pro, it’s tough to top this solution–It’s bootable, it’s relatively cheap, and it’s fast. I’ve been running this for a few months now, and it’s been completely reliable. My only complaint is with the chassis–there is a power button on the front at the bottom, which is an accident waiting to happen. However, this is minor and the price is right.

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