Backup Discussion

On the topic of backups…

I like redundancy and backups. Redundancy is this: I have more than one copy of the data on more than one disk in my important systems. So: Mirrored disks == good. This protects me from one of the disks going bad. If the system blows up, or if I simply need a copy of a file I deleted by accident, I need a copy that’s either not part of the mirror, hidden from view, or NOT on the system. Here’s how I go about that.

Having a local copy of something so that when it gets deleted, I can restore it … this is a good thing. For that, on my main workstation these days, I use automated ZFS snapshots. This pulls a painless snapshot of the data in hand every 15 minutes, every hour, every day, every week, and every month. So I can restore in 15 minute increments for the last hour, hourly increments for the last 24 hours, etc. That’s awesome. I’ve also got those applied to my local backup from Marcia’s Windows 7 system, so that I can restore from various points in time (her baseline backup period is daily, however).

But also there is disaster recovery to consider. What happens when my main system bursts into flames, or more likely just corrupts both disks due to an extreme overvoltage event that overwhelms the UPS? If both sides of my mirror pair are gone, I need to be able to restore my system. The operating side troubles me not – I can rebuild that from scratch. But I have active data in my home directory, archived (and other backups) data in a /data directory, and why not make life easy by having an offsite copy of my configuration (/etc) directory as well? What? Hey, you noticed the key word there: offsite.

For theft, fire, extreme stupidity: these problems require a remote copy of the data that can’t be destroyed by the same event that takes out the originals. Now … I’m not really over-protective of this for obvious reasons. I keep my offsite backups at work, which is less than 20 miles away. For a large regional event – basically anything involving the words “blast radius” – my offsite backups don’t qualify as far-enough offsite. But since in that eventuality, I’m likely also permanently wiped, I’m unlikely to care about the state of my offsite backups. But for every reasonable risk, copies of my data at my work site are good enough.

Now, to other risks: If my data is on disks not at home, is it well enough protected there? The answer is, “Sure.” I use encryption. These days I’m using geli whole disk encryption on my FreeBSD 10 system. Oh, and I have three rotating copies of the data, so the offsite stores get refreshed weekly on a three week cycle. That’s all rockin’, but there’s one final issue that I’ve been dealing with: Heat.

I’d previosly been using an eSata shelf installed in the system case, but for a variety of reasons, it wasn’t really working well as a hot-plug solution, so I was power-cycling the system (twice!) every time I wanted to refresh the current week’s offsite disk. I broke down and bought a lay-flat USB 3 hard drive dock from Plugable (via Amazon) a few months back. This worked really well for me for one reason above all others: I don’t have a lot of headroom between the top of the system and the top of the cabinet that houses it. So normal, upright, “toaster” configuration docks won’t work for me. But, like the “toaster” versions, the lay-flat still suffers from heat issues.

These docks aren’t inside the system chassis with managed airflow removing much of the long-term damaging heat from continuously running drives. Now … in many cases, that’s not a problems with docked USB drives: You slot a hard disk, briefly write or read, spin it down, and you’re done. But I’m synchronizing over 500 GB of data. While I’m only writing 10-30 GB on any given Monday, there’s still a lot of back and forth read and write activity that runs for the better part of 45 minutes. That’s a lot of time for the heat to build up in the disk, and not be dissipated quickly enough. To improve the long-term lifespan of these offsite disks, I wanted to remove more of the heat. While doing the initial, 6+ hour synchronization, I borrowed Marcia’s AC desk fan. It worked well enough, but was awkwardly big, and noisy, too. For the long term solution, I recently picked up a Gino USB-powered mini-fan (also via Amazon). I can plug it in, set it pointing directly down on the drive, and run my backup job without overheating the disk at all. See?

USB fan cooling USB docked drive

USB fan cooling USB docked drive

Works like a champ. Both products are Highly Recommended.

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The unasked (as yet) question that I’m about to hear is this: Why am I not just using the bog-standard and dirt cheap USB drives that one can pick up for pennies a gigabyte at the corner market?

Dirt-cheap pre-packaged USB hard drives have several strikes against them in my book. First: I’m paying for a cord, a housing, USB and power supply electronics, etc, all just to support ONE disk. With a USB dock, I can buy as many bare  hard disks as I want and use them interchangeably, with less overhead on all that other cruft.

Second: Dirt cheap means the electronics are cheap. And maybe sketchy. Or long-term unreliable. Or ? I don’t know. I can’t know. But I don’t want any issues with any part of a single, complex (yet cheaply produced) product compromising my backups.

Third (and most importantly): Disk quality. My understanding is that large system vendors and manufacturers (think Dell, IBM, HP, Fujitsu, etc) get the best quality disks – the ones that scored at the top of all the quality control checks. The second tier vendors, and the large disk resellers (think NewEgg, Amazon, and the like) get the pick of the rest of the best. And I’m told (meaning I read an article on the Internet, so it must be true) that the vendors that churn out cheap, fully packaged USB drives get the stuff from the lower third of the barrel.

Now, I’m not saying by any means that any of those disks didn’t pass quality control tests. What I’m saying is that they didn’t pass them with as much of a margin as the best disks. What does this mean for long term data storage? I’m not willing to run that experiment with my data. I’ll spend more money for higher quality disks. I actually buy the “Enterprise-grade” versions of the disks in the size and speed I require for various purposes. The price bump is on the order of 50-100% over consumer-grade disks, but the reviews and benchmarks tend to indicate that the Enterprise gear is an order of magnitude more reliable. That’s also corroborated by the manufacturer’s warranty on this grade, with is generally 3-5 years, rather than just a year.

So, buy quality products, keep them cool when running, and use encryption: the data will live a long time. That’s my story and I’m sticking to it.

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About bilborg

I am who I am, there's plenty of data on this site to tell you more. Briefly, I'm a husband, computer geek, avid reader, gardener, and builder of furniture.

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