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All cassandra capture log features and flash behavior

I use cassandra 2.2.1and noticed that after the nodetool flushcommitlog files are not deleted (in fact, maybe I didn’t see some of them, but the commitlog file is not empty).

  • What happens during nodetool flushor just a regular flush? Is all commit files supposed to be deleted during this process?

  • Is the data from commitlog used only during node repair or also during flash?

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Commitlog files are pre-allocated and reused, not deleted. This improves productivity. See here for more details .

The command log is used if the node descends before the memtable has been reset to SSTable. This is done by replaying the commitlog to recreate the memtable. When you make a flash, then the space in commitlog can be recovered and reused.

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Source: https://habr.com/ru/post/1607787/

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