How many backups should one make of their data?

Discussion in 'Mac Basics and Help' started by HarryWarden, Nov 23, 2013.

  1. HarryWarden macrumors 6502a

    Oct 27, 2012
    Do you have more than one backup of your data, such as two external hard drives? Just one? More than two?
  2. maflynn Moderator


    Staff Member

    May 3, 2009
    I maintain multiple backups.

    Here's my methodology, I use Time Machine which is great for the day to day "oh crap I deleted that type of stuff" While I can do a full system restore with that, I prefer using Carbon Copy Cloner and I clone to a different external disk. CCC is more efficient and full restores.

    Finally, I use CCC on a third portable disk that I take offsite (to my work). This provides protection against fire and theft.

    I think 2 to 3 separate backups is sufficient, and having something offsite is generally a good idea as well :)
  3. Tumbleweed666 macrumors 68000


    Mar 20, 2009
    Near London, UK.
    I do TM, CCC clone once a week or so which is then disconnected so that no malware could access it, and automated weekly incremental backups to a cloud based backup service.
  4. ChrisA, Nov 23, 2013
    Last edited: Nov 23, 2013

    ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    First decide if you need the data. If you do then make sure you always follow these two rules, even while a backup is in progress:

    1) The data needs to be on three different physical media at all times. So if you backup system over-writes the old data, you will need four copies of the data. This is one reason way incremental backup is best, no data is over written until a newer version is written. Time Machine and a few others are incremental. Two copies not not enough

    2) The data need to be always in at least two geographic locations. Even during a backup. So you would need to either rotate disk to the office, always having one there or use a cloud time off site backup service

    So three copies of the data, the live data and two backups is the MINIMUM. Here is a reasonable system

    Buy an external disk for Time Machine. This disk needs to be about 1.5 ties larger than all the data you have. The external TM disk will likely be the newest and latest disk you own. Let it run 24x7. If the computer is a notebook then maybe connect that to the airport router. But TM is your first line backup and it runs every hour.

    Next make a copy of the data using whatever software you like and keep the copy in another room onside a fire safe. When I buy a new Time Machine disk I use the old TM disk for this. It MUST be unplugged and in a good container.

    Then I subscribe to CrashPlan and let them keep a copy of my data. It takes weeks to move it all but you only do it once. Another service I like is Backblaze. The latter is MUCH simpler to set up but less flexible. Backblaze is also much faster.

    That is the minimum. If you don't like clouds then buy one more disk and one mrs fire safe and keep it at where you work or some other far away place and rotate it with the copy you keep at home.

    What are you worried about? Not a failed disk. That is easy to recover from if you have just one TM backup. You should worry about:
    1) Theft of the equipment. This is a common cause of los data. The guy will take your backup drives and anything else he can cary
    2) fire, flood, earthquake. Yes it isunlikley but everyone who lost data in a fire said a fire is unlikely. It will of course destroy the backup drives in your house.
    3) Lightening hits a utility pole down the street and 2000 volt surge kills every computer device plugged into AC. Goodthing you have a backup in the safe.
    4) Screw-ups by the operator, the OS or the software. This is the #1 cause of lost data.

    One more thing buy a new disk every year or so. Get the largest size they make, currently that is 4TB. Use that for Time Machine. Then use the old TM disk for the copy you keep in the safes and retire your oldest disk. This way none of your backup are written to drives that are more than about 4 years old. The cost is only about $120 or $150 per year. Yes the backup drives must be larger because incremental backup use spec to keep older versions. Also it is very important that the disk drives be used, writing new backups to them is a kind of test. They WILL FAIL and you want to know when that happens, so you rotate them.

    Way be so carful? If you want a photo to last for decades with 99% certainty you need more than the minimum.
  5. old-wiz macrumors G3

    Mar 26, 2008
    West Suburban Boston Ma
    the number of backups depends on how important your data is. I have three backups of my boot HDD. That's a bit excessive though.

    What happens if you lose it? Is it critical financial info? family photos?
  6. Fishrrman macrumors G5


    Feb 20, 2009
    My suggestion:

    Buy a USB3/SATA docking station, and 3 "bare" hard drives. The dock will cost only $25. Go to amazon and enter "usb3 sata dock" into the search box -- you will get many choices.

    Connect the dock to the Mac, initialize all 3 drives.

    Use CarbonCopyCloner to create bootable clones on _two_ of the hard drives. Keep one of these drives near the computer, store the other one at an "offsite location" (different building than where the computer is, if possible).

    Once or twice a week, "rotate" your CCC backups. That is, do an incremental backup of the "close-by" drive, then swap it with the "offsite" drive. Bring the offsite drive home and again do an incremental backup. Just repeat this routine at proper intervals.

    The rest of the time, keep drive #3 in the dock with the dock turned on, and use it as your Time Machine backup drive.

    This way, you will have TM "always there" if you need to recover something "only a few minutes or hours back". And the CCC backups will serve as your "data archives" for older stuff.

    CCC backups are BOOTABLE, as well. If the time comes (as it does for all) when you try to start the computer and it won't boot, just put your CCC backup into the dock, and reboot with the option key held down to bring up the startup manager. You can then select the backup, boot from it, get to the finder, and start your repair work...
  7. snberk103 macrumors 603

    Oct 22, 2007
    An Island in the Salish Sea
    You need one more copy (at a minimum) than the number of backups that will be destroyed in an accident. Then count on that one surviving HDD have a hardware failure - totally coincidentally.

    I use TM for user-errors. I do a cloned backup nightly to an external HDD that I rotate through a safety deposit box. I have a minimum of 3 external HDDs - two at home and one off-site - so that if one goes bad I can continue the rotation until I get a replacement.

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