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Re: Filesystem snapshots



On 04/23/2016 09:17 PM, Scott Wheeler wrote:
> On Apr 23, 2016, at 9:03 PM, John <john@commonpeople.uk> wrote:
> 
> You don't have to copy the whole data set -- that's the whole notion
> behind "copy-on-write".  LLVM (or any copy-on-write system) only has
> to note the inode tree in the snapshot and then store the live data
> as a set of changes against that (i.e. update its inode tree to point
> to the changed blocks).  This makes snapshots fast.
> 
> (Note: I've never actually used LLVM to do this, but that's the basic
> logic behind copy-on-write systems.)
> 
> -Scott

Yeah, I agree with John.
I don't use LLVM, I use BTRFS, but the way to go is to snapshot your
system and backup the snapshot. You'll back up a slightly outdated
version, but that doesn't matter.

A copy on write filesystem will basically just create a second pointer
to your home and only create copies for the snapshot when a block
actually changes.

Cheers,
Bennett

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