<b>This week in caching: Varnish for people past the quickstart</b>

<b>This week in caching: Varnish for people past the quickstart</b>
Four for anyone running VCL in anger.
— <b>grace mode is the killer feature</b> — <code>std.healthy()</code> plus a grace window serves stale during backend outages; this is Varnish's real superpower, not raw speed.
— <b>ban vs purge</b> — purge is exact-match and instant; bans are lazy regex invalidation evaluated on next fetch. Use bans for "flush everything under /blog/".
— <b>req.hash_always_miss for cache warming</b> — force a refresh without evicting the live object.
— <b>hit-for-pass, not hit-for-miss</b> — understand why caching an uncacheable response as "don't cache me" prevents request serialization stampedes.
<b>Bookmark:</b> the Varnish Book's grace+saint-mode chapter — still the clearest explanation a decade on.