DataStax Academy FAQ

DataStax Academy migrated to a new learning management system (LMS) in July 2020. We are also moving to a new Cassandra Certification process so there are changes to exam bookings, voucher system and issuing of certificates.

Check out the Academy FAQ pages for answers to your questions:


question

xiaowan2_157616 avatar image
xiaowan2_157616 asked ·

one node experiences MemtablePostFlush pending

I ran nodetool tpstats and see MemtablePostFlush is pending

MemtablePostFlush 1 647 8803 0 0

and I re-ran the same command after a while and still got the same. I also re-start DSE and issue still existed. please help to address it.


Thanks


memtablepostflushtpstats
10 |1000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 1.0 MiB each and 10.0 MiB total.

1 Answer

Erick Ramirez avatar image
Erick Ramirez answered ·

@xiaowan2_157616 The MemtablePostFlush task cleans up the commit log after the memtable data is flushed to disk. The high number of pending tasks indicates that the Cassandra process is not able to access the commit logs. It's highly likely that logs have the wrong file permissions.

Check the permissions of the commitlog (and its parents). Also make sure that the log files are owned by the same OS user as the Cassandra process (cassandra user by default) instead of root. You will need to perform a restart after you have reset the permissions. Cheers!

Share
10 |1000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 1.0 MiB each and 10.0 MiB total.