drobo, day 9

It’s been just over a week with the drobo.

The media copy-and-swap thing went well; with one drive in the system, the drobo took on about 600GB of nonredundant data. The red LED next to the following drive bay indicated that the unit was cranky, so after popping the four-year-old stock 160GB drive back in my G5, I added the two 320GB drives that I had just pulled from the G5’s internal drive bays into the drobo. I did this while the system was still copying data to the 750GB drive — not terribly impressive but I did want to make sure that the hot-swap capability of the drobo at least partially worked as advertised.

One interesting thing that the drobo does — since it “fools” the host OS into thinking that it’s one or more 2TB partitions regardless of the actual space available, rather than returning a hard out of space error back to the OS, the drobo just starts stalling writes, making write access slower up until the point that it’s basically blocked on write. I ran into this while filling the 750GB drive before the replication stuff had fully mirrored onto the 2 320GB drives.

It took about a day for the drobo to indicate that it was finished mirroring the data across the 1.2TB of raw drives within. When finished, I had about 660GB of redundant storage, which is about what one would expect (maybe slightly better) from a RAID setup. I was somehow hoping that they’d have a magic algorithm that’d get me a little more redundant space — but for another $200 or so (for another 750GB drive) I could boost the system to about 1.1TB of redundant storage.

Video playback from the drobo is adequate enough to keep up with 720p content. I’m not so great at the math, and since USB2.0 real-world speeds vary pretty widely, I was somewhat concerned that HD playback might suffer from the limited bandwidth of USB as opposed to, say, FireWire 800, but this turned out not to be a problem.

If you’re following closely you might have noticed that I bought a $500 storage system and a $200 750GB drive, took 2 320GB drives out of service, and added a 160GB drive as a boot volume. Did I actually gain any space with these purchases? Actually, not really. The drobo is essentially using the 750GB and the 2 320’s as a redundant 640GB disk. Any added space I have is because I’ve shuffled the OS and applications and some other non-media items onto the 160GB boot volume. In practice, this turned out to be about another 100-140GB of space available for content on the drobo.

Since there wasn’t really any major net gain in storage space (maybe 20%?), I guess the real value in the drobo comes from redundancy and ease of configuration. Was the setup path to essentially a large RAID easy? Hell yeah, even the least tech-savvy user could do it, and I really only spent about 10 minutes of active time on the system’s setup. Is redundancy really relevant in a world in which most media can be replaced over the Internet at no cost? I’m not entirely sold on this one yet — there are home movies and iTunes albums and other digital assets — which cost me either real hard cash or real hard time — now safely on at least two hard drives, where previously there was perhaps only one copy on some fragile platter inside the G5’s big JBOD concatenated disk array.

I have only once ever had a hard drive fail on me. This was some weird prototype item I got from a family member who worked at IBM’s Almaden Storage Research Facility, it failed in a most spectacular way under OPENSTEP/Mach some time ago. Am I uncommonly lucky? Or is redundant storage for the home a sham — is 100,000 hours MTBF really just good enough for most of us? Bottom line, the drobo is nice because it solves the problem of an external housing for additional drives as well as the management of said drives in a push-button simple sort of way. There are crazier solutions but I don’t want to spend any more time debugging the home media center than I have to.

As a side note the same drives in the drobo are much quieter than they were inside the G5 — must be some kind of anechoic housing going on there.

Nothing sucks more than seek noises during a really good movie, I guess.

And those blinking lights are totally rad.