Time Capsule vs. AEBS vs. NAS, reliability and performance questions

Discussion in 'Mac Accessories' started by theosib, Dec 18, 2011.

  1. theosib macrumors member

    Joined:
    Aug 30, 2009
    #1
    I am aware that the Time Capsule is the only Apple-sanctioned solution for network backups. I am also aware that Time Capsules have a reputation for being unreliable (power supply failures mostly), and it's not clear what Apple has done to rectify this. Moreover, single mechanical hard drives are themselves ticking time-bombs, which is why enterprises prefer RAID solutions.

    There are some NAS solutions, like QNAP, that claim to support Time Machine. I can say from personal experience that Netatalk isn't exactly the most robust software, so I'm not sure how I feel about trusting my backups to it. But this is one good and relatively inexpensive way to do TM backups to RAID.

    While trying to come to a final decision, I've been using USB drives attached to an AEBS. One thing that's irritated me is that backing up any significant amount of data to this would crush my new 2011 17" MacBook Pro with 8GB of RAM. In this configuration, TM seems to be a massive memory hog. One hypothesis that occurred to me was that since TM is backing up to a sparsebundle, which is an encapsulated filesystem, uncommitted writes will be buffered, which will compete for RAM against applications. The sparsebundle is actually a set of files that are stored on the network volume, and that too will be buffered. Thus, every write will be buffered twice (at least). On top of that, since the host is much faster than the network, the channel to the disk will fall behind, consuming more and more memory as more unwritten data is buffered. Just a guess.

    It never occurred to me that a real Time Capsule would be any different. But I was talking on IRC with a guy who claims to be friends with several Apple engineers. This anonymous person, whose word I take with a grain of salt, claims that the way backups are done to a TC is completely different to how they're done to a USB drive on an AEBS. He claims that a great deal of the overhead associated with managing the backup sparsebundle is offloaded to the Time Capsule. As a result, backups to a TC will impact the rest of the system much less. In researching this, I have come to find out that although you can export a TC backup bundle to an external drive, you cannot import one, partly because the on-disk formats are different. That Apple might use a completely different protocol to back up to a TC seems plausible and might explain some of the reported reliability differences between AEBS and TC setups. I'm assuming that AEBS and a NAS solution would really use the same protocol (AFP). Can anyone back up any of these claims?

    Can anyone comment on the relative reliability of NAS, AEBS, and TC solutions in terms of data integrity?

    What about the reliability of newer TC units in terms of hardware failures?

    And how about performance?

    If I've used Parallels, and it's taken a snapshot, many gigabytes will get backed up. When you encounter such a situation, what impact on system performance is there, and how long does it take to back up?

    Thanks for the help!
     
  2. flynz4 macrumors 68040

    Joined:
    Aug 9, 2009
    Location:
    Portland, OR
    #2
    Although I have owned several NAS RAID arrays (usually configured in RAID-5)... I have come to the conclusion that RAID is good technology for enterprise, and a poor technology for consumers. The biggest problem is that RAID is too fragile for consumers since they require the use of homogenous drives. They almost all need the same size drives, often need the same drive manufacturer, and some even require the same model and firmware revision. This is OK when you are enterprise where you stock spares... but it is out of sync with consumer behavior.

    Things like DROBO and WHS solve some of the challenges, and are better home technology IMHO for those requiring HDD array redundancy.

    I have changed my backup methodology to use single drives for local backup... combined with automatic offsite cloud storage. This gives me 3 layers of redundancy including primary data on iMac, local storage using TM/TC, and cloud backup using Crashplan+. With this change... I do not feel like I need my local backup to be protected by RAID. In other words... I've provided the redundancy at a higher, and hence more secure level.

    I have switched completely to Time Capsules for local backup. I have 4 of them total. A 3TB TC backs up my primary iMac, which holds 100% of my original data. A second 2TB TC is used to back up our MacBook Airs automatically whenever we are home. I've provided each of my college age daughters with a 2TB TC to back-up their iMacs and MBAs. All iMacs and MBAs (as well as a couple of windows machines) are cloud backed up to a Crashplan+ family account which is a steal at just $6/month.

    I am not a believer in any backup methodology that relies on human interaction of any kind. Humans are too error prone. Before secure offsite cloud backup was affordable, manual offsite backup was about the only viable option. With cloud backup so cheap to deploy, combined with its extreme security... I think anyone who doesn't use the cloud is nuts. Having said that... I still occasionally (maybe once/year) load up my data onto a 2TB USB drive and store it offsite. The chances of ever needing it are approximately 0%... but old habits are hard to break. I suspect that I'll eventually kick that old obsolete habit. :)

    /Jim
     
  3. driftless macrumors demi-god

    driftless

    Joined:
    Sep 2, 2011
    Location:
    Chicago-area
    #3
    Interesting thread. I have a small home office and backup via Time Capsule, Dropbox, etc. I keep rejecting adding another physical drive into the equation after each research foray and have started to look for a "volume" cloud back up option. And, no, iCloud is not an option as I am backing websites, photo libraries, etc. Like Jim, I want my backups, whether primary or redundant, to be automatic. What I would really like is for my Time Capsule to be automatically backed up, via cloud preferably.
     
  4. flynz4 macrumors 68040

    Joined:
    Aug 9, 2009
    Location:
    Portland, OR
    #4
    Back when I was backing up all of my PCs (before I switched to Macs)... I was backing up all our machines to a WHS machine... and I was running program that would make back-ups of my backup sets. I thought I was being clever and extra safe, but as I researched backup strategies, I realized I was making a mistake.

    I will encourage you to reconsider the bolded section above.

    It is generally considered that backing up back-ups is not desirable for a few reasons. The most important reason is because any error in the backup (for whatever reason)... becomes propagated in the "backup of the backup".

    It is generally considered that redundant and independent backups is the best approach to backups. Every backup program has its own idiosyncrasies. None are immune to failures... either in the program itself, or in user settings. Having two (or more) independent backup solutions is much less susceptible to such errors.

    My criteria for a backup strategy is as follows:

    • At least two independent backup systems
    • One MUST be offsite (for disaster recovery)
    • The second ideally is local (for ease of recovery)
    • Both must be fully automatic, with no human intervention
    • Ideally one (or both) have full versioning... including protection from inadvertent deletions

    I personally think that Time Machine is a pretty spectacular program for local backups. The user interface for restoring versions, or inadvertent deletions is unmatched. It is also great for data migration if/when you decide to upgrade .

    For cloud backup, the leading candidates seem to be Crashplan+, Mozy, Carbonite, and possibly a few others. I personally use CP+. It is very inexpensive ($3/month for unlimited backup). They also have a family plan for $6/month for all of your family computers. In my case... even my college kids are covered. My largest backup set is our home iMac, which is 1.2TB.

    /Jim
     
  5. driftless macrumors demi-god

    driftless

    Joined:
    Sep 2, 2011
    Location:
    Chicago-area
    #5
    Right, I should have written that has having duplicate back-ups of the original. I have started to look at Crashplan+.
     

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