scylladb

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Botond Dénes b24bd4d176 Merge '[Backport 5.4] Reduce TWCS off-strategy space overhead' from Raphael "Raph" Carvalho

Normally, the space overhead for TWCS is 1/N, where is number of windows. But during off-strategy, the overhead is 100% because input sstables cannot be released earlier.

Reshaping a TWCS table that takes ~50% of available space can result in system running out of space.

That's fixed by restricting every TWCS off-strategy job to 10% of free space in disk. Tables that aren't big will not be penalized with increased write amplification, as all input (disjoint) sstables can still be compacted in a single round.

Fixes https://github.com/scylladb/scylladb/issues/16514.

(cherry picked from commit b8bd4c51c2)

(cherry picked from commit 51c7ee889e)

(cherry picked from commit 0ce8ee03f1)

(cherry picked from commit ace4e5111e)

Refs https://github.com/scylladb/scylladb/pull/18137

note for maintainer: first cleanup (conflicting) patch was removed and doesn't change anything.

Closes scylladb/scylladb#19549

* github.com:scylladb/scylladb:
  compaction: Reduce twcs off-strategy space overhead to 10% of free space
  compaction: wire storage free space into reshape procedure
  sstables: Allow to get free space from underlying storage

2024-07-09 14:36:27 +03:00