"snapshot" RAID

[Dan Ritter]

On Sun, Mar 28, 2010 at 04:01:37PM -0400, Tom Metro wrote:
> Dan Ritter wrote:
> > No. I just need it to be able to boot enough to access the disk
> > and network. At that point I can figure out why I couldn't boot
> > from the first disk, replace it and reinstall the OS, if needed.
> 
> Ah, so you're just using the second disk as 1. a bootable rescue disk, 
> plus 2. snapshot archival storage.
> 
> I'd rather have a second disk be as close to a mirror as possible, so if 
> something fails on the primary, you can immediately continue productive 
> work with the secondary (after a reboot, of course). (The secondary 
> would still serve the purpose of a rescue disk, and you can use it to 
> investigate the problem later.)

That doesn't solve the oops problem. The other day I realized
that in editing a command line, I had done this:

  rm ../../longprefix *

instead of 

  rm ../../longprefix*

but since the directory was more than 24 hours old, all I had to
do to recover was say:

  cd ../../
  rsync -a /snapshots/blackbox/home/dsr/pathpathpath/ ./

whereas a RAID mirror would not have helped at all.

Losing data this way is more common than catastrophic disk or
filesystem failure in my experience, so recovering from it
gracefully is more useful.

That said, my primary data storage at home uses both RAID and
rsnapshot.

-dsr-

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