[Varnish] #1605: Resize a storage backend at runtime

[Varnish]

#1605: Resize a storage backend at runtime
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 Reporter:  mattrobenolt  |       Type:  enhancement
   Status:  new           |   Priority:  normal
Milestone:                |  Component:  varnishd
  Version:  unknown       |   Severity:  normal
 Keywords:                |
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 I talked about this with phk in IRC a while back, so documenting here.

 It would be really awesome to be able to size up/down the storage backend
 without restarting and dumping the whole cache.

 Typically, this is really only important when you're initially trying to
 size your cache correctly.

 Say you get a machine with 96G of RAM dedicated to varnish, and we want to
 tune it just right without waste or going over.

 My process today is such that I set our -smalloc to ~50% of RAM and let
 the cache fill up until it starts evicting objects because of space
 (n_lru_nuked). Then I increase, and try again, but I need to start with an
 empty cache every time.

 Increasing the cache size should be much easier to handle, since it's just
 adding more space. But downsizing would require immediately evicting all
 the old objects until achieving the desired size.

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Ticket URL: <https://www.varnish-cache.org/trac/ticket/1605>
Varnish <https://varnish-cache.org/>
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