[ET Trac] [Einstein Toolkit] #180: Reduce disk space used by checkpoints

[Einstein Toolkit]

#180: Reduce disk space used by checkpoints
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  Reporter:  hinder       |       Owner:  mthomas
      Type:  enhancement  |      Status:  new    
  Priority:  major        |   Milestone:         
 Component:  SimFactory   |     Version:         
Resolution:               |    Keywords:         
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Comment (by eschnett):

 SimFactory's philosophy is that each restart is independent of the other
 restarts, like a snapshop of the simulation in time. The hard-linking
 mechanism was introduced to prevent Cactus from (accidentally?) deleting
 data from old restarts.

 One problem in long-running simulations is that (a) one may accidentally
 delete too many checkpoints, so that the simulation becomes unusable.
 Another problem is that, if an error in the simulation is detected and if
 all old checkpoints have been deleted, it is impossible to "go back in
 time" (using checkpoints left every so many time steps).

 My current idea is to archive old restarts, and then delete them (or parts
 of them) locally. In this way, no data have to be deleted. This depends on
 the availability of archival storage, but this should be present -- we
 mostly have not been using it because this is somewhat awkward: it takes a
 long time, different systems have different archives, and it is cumbersome
 to find out which files have been archived. However, it should in
 principle be straightforward to automatically copy older restarts into an
 archive.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/180#comment:1>
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