Averting Disaster - A Guide To Computer Backups (2014)
by Brett Howse on May 21, 2014 9:00 AM EST- Posted in
- IT Computing
- Mac
- Apple
- Windows
- Cloud Computing
- macOS
Plan Your Backups
No matter what kind of a backup system you end up using, you need to start with a plan. To be successful, there are a couple of things that need to be ironed out first:
- Where is your data now? Do you keep your data organized in your Documents, Photos, Music, and Videos folders? Is it on a NAS device? External hard drive? While not essential to performing backups, knowing where you keep your data is going to make the process easier. The more it is spread out, the more difficult it is to back it up – not impossible – but more difficult. Some of the built-in backup tools assume your files are in fact in your user folder, or at least your libraries, so take the time now to figure out where your important data is. Other backup programs will scour the entire computer for files, so if you have files everywhere, there are solutions for this as well.
- How important is your data? Is it all about equally important, or is there some data where you don’t want to lose it, and other data where it’s crucial you don’t lose it? It’s possible to do full backups to a local backup target, but also back up your most important data offsite.
- How much risk do you want to mitigate? The easiest backups will be to an internally or externally attached hard drive, which will protect against equipment failure, or user error. Moving up, you can back up to a NAS on your LAN, which will add a possibility of mitigating theft (but certainly not a guarantee) as well as giving you the option of backing up multiple machines. For ultimate protection, some sort of offsite backup is required. This is the only way to mitigate the risks of fire, flood, theft, and natural disaster. If the data is extremely important, you may even want to ensure the data is backed up to multiple geographic areas to ensure recovery from a natural disaster.
- How much space are you going to require for backups? If you are doing Image Level backups as well, factor in that you will need a backup target larger than the total amount of data you want to back up. The more space you have, the more versions of files and the farther back in time you can go to perform a restore. It would be prudent to start with a backup target that is at least twice as large as your total data to be backed up.
- What is your RPO? Are nightly backups good for you, or do you need to perform backups more often? Do you need continuous backups? It is essential to define an RPO that works for you.
- What is your RTO? Cloud based backups are wonderful because they are offsite, but the amount of bandwidth required to recovery multiple terabytes of information will be quite significant. If you aren’t worried about time, then it may be fine for you, but if time is a factor you may want to ensure you have some sort of local backup as well as offsite. RTO also factors in to the backup equipment decision. Optical media can be used as an offsite backup method, but recovering the data will be labor intensive and slow.
- What is your budget? For a single PC, you can configure a backup using just optical media, or an external hard drive, either of which will not be overly expensive. For multiple PCs, you may want to invest in a NAS or server to back up to. You can also expand the backups to the cloud for monthly or annual fees depending on the backup system you decide to go with. Just remember though that the cost of your backups may potentially save you from a much higher cost if disaster ever strikes.
- How much time are you willing to spend performing backups? Actually, this is a trick question. While it is possible to do a backup plan based on burning files to a DVD, and then storing these discs for later use, the fact is that unless a backup system is completely seamless, odds are that it’s not going to be used. In this day and age, there are many ways to perform backups without having to do anything but the initial set up, and for this reason there isn’t much point in doing anything manually.
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patrickjchase - Thursday, May 22, 2014 - link
ZFS RAIDZ implements strong checksums within each drive, such that it can reliably detect if a drive is returning bad data and ignore it. In some respects it's actually stronger than RAID6 in terms of its ability to deal with silent corruption. That's why NonSequitor wrote "double parity OR checkums" (RAID6 is double-parity, RAIDZ is single-parity augmented with strong per-disk, per-chunk checksums).If you're halfway competent then it's not "extremely likely" that you'll encounter unreadable sectors during a RAID5 rebuild. There's a reason why both good RAID controllers and ZFS implement scrubbing (i.e. they can periodically read every disk end to end and remap any unreadable sectors). If you do that every couple days then the likelihood of encountering a new (since the last scrub) unreadable sector may or may not be high depending on your rebuild time.
For example I have a 5-disk RAID5 array that I use for "cold" storage. I scrub it daily, and rebuilding to a hot-spare takes 6 hours (I've tested it several times, verifying the results against separate copies of the same files), which means that the maximum delay between the most recent scrub and the end of a rebuild is 30 hrs. The scrubs have only found one bad sector in ~2 years, so I respectfully submit that the likelihood of an additional failure within 30 hours of a scrub is pretty darned low.
beginner99 - Thursday, May 22, 2014 - link
exactly. anything above 2 TB drives becomes really problematic in this regard. With 4 TB drives it's almost guaranteed a RAID-5 rebuild will fail. IMHO if you do RAID, do RAID-1.patrickjchase - Thursday, May 22, 2014 - link
RAID1 has exactly the same problems as RAID5 - In the case of silent corruption it can't determine which disk is bad, and it's vulnerable to a single disk failure during a rebuild. The likelihood of such a failure is obviously lower (now you only have to worry about 1 other disks instead of 2 or more) but not hugely so. RAID6/RAIDZ2 is statistically much better until you get up to really high drive counts.The "big boys" with truly mission-critical data do N-way replication, i.e. all critical data is replicated (n>=3) times on different systems.
jimhsu - Wednesday, May 21, 2014 - link
+1 to crashplan. For my most important data, I have n+2 backups: n being the number of computers I have (meaning that Onedrive automatically syncs them); 2 being a crashplan online subscription as well as a local crashplan backup. I also have restore previous versions running, and use it on occasion, but don't consider it a backup per se.pjcamp - Wednesday, May 21, 2014 - link
I plowed through all the competitors a few years ago, and Crashplan was the one I selected. It had the cheapest unlimited storage with version history, and the (for me) killer feature that there exists a Linux client. I have a FreeNAS box that I use for media storage. I can mount it as a drive on my Linux machine and the Crashplan client will back it up just as if it were a local drive. There is also an Android client that gives you access to all your files, functioning as a sort of personal Dropbox, without sharing but with better security.I've had occasion to use my backups a couple of times and found it easy and speedy, much more so than I expected for a cloud service.
cknobman - Wednesday, May 21, 2014 - link
Everything in my house goes to a personally built server onto dedicated RAID storage drives. No accounts other than my personal administrator account have access to do anything but read.Those drives are then backed up to the cloud via CrashPlan.
Simple, effective, and as foolproof as I can get for now.
uhuznaa - Wednesday, May 21, 2014 - link
One thing to note with Time Machine: You don't need to use the fancy interface for restoring files. Just browse your backup disk with the Finder (or on the command line), there's a directory for every backup from which you can just copy things over.To CrashPan: I used that for a while, but found it to be utterly uncontrollable. The log files are a joke, the status mails arrive at random times (or not at all) and are useless ("Files: 117k, Backed Up: 99.9%") and often enough when a backup didn't run for some reason it's impossible to debug because there's no real error reporting. It may work somehow, but it has all the marks of something I don't want to rely on.
NCM - Wednesday, May 21, 2014 - link
Yes, that's indeed a big point for Apple's TimeMachine — that and it being included free with every Mac. If necessary you can just go digging into a TM archive and pull out what you need.SkateboardP - Wednesday, May 21, 2014 - link
Hi Brett,great guide but can you or others please check if the OneDrive backupsolution is throttled and capped at 355kb/s under win8.1 (Desktop)? I read that many people complaining about that. Thanks.
plext0r - Wednesday, May 21, 2014 - link
I've been using Duplicati for a few years and it has been good. "It works with Amazon S3, Windows Live SkyDrive, Google Drive (Google Docs), Rackspace Cloud Files or WebDAV, SSH, FTP (and many more)." It uses rsync under the covers and I use it to backup to my RAID-5 NAS in the basement. I also perform offsite backups (rotate 1TB disks to and from my workplace).