6 drives / terabytes in a Mac Pro

**UPDATE:** I'm [selling my MaxConnect](/journal/2010/10/16/fs-sony-tx7-verizon-blackberry-tour-9630-more/), which allows the addition of 2 drives in 2006-2008 Mac Pros (in the lower optical bay). I nearly ran out of space in my Mac Pro the other day, and it was painful. I had 4 x 500GB drives in the machine with an additional 4 x 500GB attached in various enclosures connected via Firewire 800, Firewire 400, and USB 2.0. I also do backups onto 2 NAS boxes and a standalone server, which hold a total of just over 6 more terabytes. Backups over the network are pretty painful on the Mac; all backup apps I've tried so far are about 3x slower when copying over the network than are comparable programs running in the Windows environment. As a result, I've migrated to primarily doing local backups.

Anyway, so I nearly ran out of space on my main working drives, which is where most of my photos and video work is stored. Luckily, music, movies, and ripped tv shows are stored on a NAS box; otherwise, this would have happened long ago.

Originally, this was my internal Mac Pro drive and volume configuration:

> A: 1 x 500GB System B: 2 x 500GB RAID 0 (striped, 1TB accessible) Data 1 C: 1 x 500GB Data 2

B and C filled up, and I was starting to use A for image storage, which was not ideal. I hate storing data on my system partitions because it makes reinstalling everything too complicated.

So here's what I did. I bought a MaxConnect for Mac Pro, which allows the installation of two SATA hard disks in the space normally occupied by a second optical drive. Here's what the product looks like:

I ordered six Hitachi 1TB hard drives (enterprise versions, whatever that means). They claim a "target" of 1.2 million hours MTBF (137 years), but considering that 1 out of the 6 drives was DOA, I don't believe them. Anyway, I installed the six drives and partitioned them as recommended by the Mac Pro Performance Journal. Disk Utility.app is a little buggy and required several reboots in order to partition and software RAID all the drives as suggested, but everything basically worked as described.

Note that this installation is easy if you're used to building your own systems, but if you're a Mac guy who has only opened up your system to admire its internal beauty, you may not want to attempt using the MaxConnect. Routing cables around inside a Mac Pro isn't as easy as it could be!

Here's my new partition and volume configuration:

> A2: 20GB partition x 6 = 120GB RAID 0 (striped) fast partition for PS3/Final Cut scratch B2: 65GB partition x 6 = 195GB RAID 1+0 (striped over mirrored) boot partition C2: 850GB partition x 6 = 2.5TB RAID 1+0 (striped over mirrored) data partition

I'm now completely mirrored while still having a performance boost from the striping. I have a super-fast partition for scratch space and temporary work, and I can lose any one disk without losing real data. If I lose a disk, I have a 60% of surviving a second drive failure at the same time. Also, see a discussion about RAID X+Y vs RAID Y+X. It seems to make sense, and is why I chose RAID 1+0 over RAID 0+1.


Disk Utility.app is a mess!

Unfortunately, I only gained 43% in accessible disk space by adding 200% in actual disk space, but the mirroring is worth the extra cost since I've got my entire life's worth of photographic work sitting on the drives.

Performance

My RAID buddies out there hate disk benchmarking utilities, but I don't know of any other way to measure performance. I ran Xbench and got the following numbers:

Sequential Stock
250GB/7200
6-Drive
RAID 1+0
6-Drive
RAID 0
Uncached Write [4k blocks] 87.28 MB/s 356.82 MB/s 383.97 MB/s
Uncached Write [256k blocks] 64.32 MB/s 225.70 MB/s 321.53 MB/s
Uncached Read [4k blocks] 28.30 MB/s 19.80 MB/s 21.45 MB/s
Uncached Read [256k blocks] 73.19 MB/s 195.44 MB/s 422.62 MB/s
Random      
Uncached Write [4k blocks] 1.24 MB/s 4.15 MB/s 14.25 MB/s
Uncached Write [256k blocks] 23.67 MB/s 84.80 MB/s 141.05 MB/s
Uncached Read [4k blocks] 0.63 MB/s 2.04 MB/s 4.88 MB/s
Uncached Read [256k blocks] 25.52 MB/s 48.63 MB/s 84.27 MB/s

Who knows if the numbers are accurate? I get slightly different results every time I run the thing.

In any case, I'm happy now and have just over a terabyte of free space available locally, which should be sufficient for the next year or two.

I also ordered a WiebeTech RTX400-SV, a four-bay external eSata system that allows drives to be inserted like removable disks. All the data travels on a single eSata cable thanks to Steel Vine (port-multiplied eSata) technology. I think this setup will work out just fine for the immediate future. Next time, I may go with an Apple xServe RAID wired via fiber to a remote closet. :)

By the way, I buy most of my computer hardware from NewEgg (affiliate link), which has never failed me. They have a simple online RMA program, so if anything arrives DOA or has a problem within the return period, returning it is easy.

Finally, here are two hints for the installation of the MaxConnect and the max_flow fan system for the Mac Pro:

  1. Be sure you adjust the screws on the bottom of the top bay in the Mac Pro properly. Otherwise, the MaxConnect frame will not slide all the way in. The front of the MaxConnect tray should be 15mm from the front of the front lip of the bay when it is installed in the right place. If it isn't pushed in far enough, the DVD drive tray may snag when you try to open and close it.
  2. When mounting the max_flow fan for the lower memory riser card, mount it so it does not touch the bay's metal frame. If it touches, you will hear an annoying, high-pitched resonance when the fans run.