The parameter DiskSyncSize
is a MySQL Cluster parameter and was added in MySQL 5.1.23.
After the amount of stored bytes of data per file, the data node will fsync
(flush) the LCP file to disk, even if a fsync
is not needed for consistency.
This is done because the OS will otherwise buffer all the writes, and when a fsync
is really needed, it can take a lot of time...
Originally this parameter was hard coded. Now it defaults to 4 Mbyte.