CODEWITHSUNDEEP
cassandracassandra-3.0
Bob Bedinsky
Bob Bedinsky

Reputation: 81

sstableexpiredblockers: what to do having blocking SSTables in Cassandra?

I have realized that some sstables are not dropped even if they contained only tombstones. Using a manual major compaction these sstables are removed. Perhaps it needs to update unchecked_tombstone_compaction to true along with gc_grace_period

I have seen utility sstableexpiredblockers utility that will reveal blocking SSTables that prevent an SSTable from dropping.

During compaction, Cassandra can drop entire SSTables if they contain only expired tombstones and if it is guaranteed to not cover any data in other SSTables. This diagnostic tool outputs all SSTables that are blocking other SSTables from being dropped.

I do not understand:

... if it is guaranteed to not cover any data in other SSTables ...

Since my compaction strategy is TimeWindowCompactionStrategy, all sstables have different time intervals.

I would like to know how handle those blocking SSTables.

Upvotes: 7

Views: 529

Answers (1)

Chandan Goel
Chandan Goel

Reputation: 21

Just looked at it(bit late). You may check if the NTP server pool was set up during installation. This can be a big reason of clock not getting synched.

Also, it has been seen that instead of relying on VM, it is a good idea to use a physical machine for this purpose.

Upvotes: 1

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