Bug #74317 Fix problems in disk_write_speed ndbinfo tables
Submitted: 10 Oct 2014 13:02 Modified: 9 Jan 2015 10:11
Reporter: Mikael Ronström Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Cluster: Cluster (NDB) storage engine Severity:S3 (Non-critical)
Version:7.4.0 OS:Any
Assigned to: CPU Architecture:Any

[10 Oct 2014 13:02] Mikael Ronström 
Description:
In #WL7509 to MySQL Cluster 7.4.0 a number of new ndbinfo tables was added to report on the disk write activity.
There was some confusion in these tables as some of the fields reports in bytes per second and others in kbytes per
second and others even in number 40 bytes per second.

There was also a conversion error in calculation of the standard deviation

How to repeat:
Standardise on reporting in bytes per second in all cases

Fix the calculation of standard deviation
[24 Mar 2015 23:01] Todd Farmer 
Documented fix in the NDB 7.4.3 changelog as follows:

    Values in different columns of the ndbinfo tables
    disk_write_speed_aggregate and disk_write_speed_aggregate_node
    were reported using differing multiples of bytes. Now all of
    these columns display such values in bytes.

    In addition, this fix corrects an error in calculating the
    standard deviations used in the
    std_dev_backup_lcp_speed_last_60sec and
    std_dev_redo_speed_last_60sec columns of the
    ndbinfo.disk_write_speed_aggregate table.

Also updated the descriptions of the affected tables/columns in the Manual
accordingly.