Mac – Time Machine backup volumes (eg straight disks vs. Time Capsule)

What’s the best backup strategy when using Time Machine?  Want ease of life and low cost.  Sometimes I have more than one instance of Mac OS on my Mac, e.g. on different hard drives, and these require to be backed-up onto their own unique volumes.   The following represents my best understanding of the matter so far, based on web-trawling and received expert advice, but I am a beginner, still trying to orient myself in the world of Macs.

  1. Time Capsule
    • Acts as network hub with WiFi and own backup volume plus the ability to connect (via USB) to shared printer/USB drive etc.
      • You can for example plug it into your broadband modem or router
    • Can support Time Machine from multiple Macs, provided they are named differently; it automatically creates similarly-named folders for each Mac.
    • It costs about £235 for a 1TB unit.
  2.  Generic network (NAS) drive
    • Where there is already a network in place, this can simply be connected (via Ethernet) to one of its hubs (e.g. a router).
    • To allow for multiple Macs, one would presumably have to manually divide the disk into separate partitions, each of which would serve as a unique backup volume for a single given Mac.  Care needed not to accidentally mix them up / overwrite.
    • Cost is about £100 for a 0.5 to 1TB units(depending on make & supplier)
  3. USBdrive
    • Could be connected directly to USB port on the Mac in question.  Or, could be connected to a network hub with USB ports (making it like a network drive).
    • Regarding multiple Macs, same argument as for network drives?
    • Cost can be as low as £47 for a 0.5TB device.

Not sure about the multiple Macs sharing a common backup device.   If one had already started using a storage device for a particular set of Macs (maybe only one Mac), then at a later stage required to add support for a further Mac, would this be straightforward?

  1. For a Time Capsule, would one simply point the new machine at it and it would get added automatically?
  2. For a plain (non Time Capsule) disk, would it be possible to add a new partition?   Would that be straightforward or would some special measures be needed e.g. to adapt to the repositioning of blocks that can occur during partitioning?  Presumably it would make no difference if it was a network drive or USB drive (?)

Some things (I imagine) in favour of a straight USB drive over a Time Capsule:

  1. It can be small (even pocket-sized) and light, hence easily carried to various locations, whereas the Time Capsule appears more intended for being left in a base location, where it can serve as a WiFi router.
  2. Although a Time Capsule will automatically create folders for each uniquely-named Mac, what happens if it encounters two Macs of the same name, i.e. could one of them corrupt the other one’s existing backup data?


  1. Can a Time Machine backup volume itself be backed up (or cloned) ?
  2. When a Time Machine backup volume gets full, the oldest backups are deleted.  Is there a way to keep certain “milestone” backups as permanent?  For example the machine’s initial clean installation or, just after this, when updated and user-configured.

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