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18.5.10.10 The ndbinfo disk_write_speed_aggregate Table

The disk_write_speed_aggregate table provides aggregated information about the speed of disk writes during LCP, backup, and restore operations.

The following table provides information about the columns in the disk_write_speed_aggregate table in NDB 7.4.3 and later; information about disk_write_speed_aggregate in NDB 7.4.2 and earlier can be found later in this section. For each column, the table shows the name, data type, and a brief description. Additional information can be found in the notes following the table.

Table 18.350 Columns in the disk_write_speed_aggregate table

Column Name Type Description
node_id integer Node ID of this node
thr_no integer Thread ID of this LDM thread
backup_lcp_speed_last_sec integer Number of bytes written to disk by backup and LCP processes in the last second
redo_speed_last_sec integer Number of bytes written to REDO log in the last second
backup_lcp_speed_last_10sec integer Number of bytes written to disk by backup and LCP processes per second, averaged over the last 10 seconds
redo_speed_last_10sec integer Number of bytes written to REDO log per second, averaged over the last 10 seconds
std_dev_backup_lcp_speed_last_10sec integer Standard deviation in number of bytes written to disk by backup and LCP processes per second, averaged over the last 10 seconds
std_dev_redo_speed_last_10sec integer Standard deviation in number of bytes written to REDO log per second, averaged over the last 10 seconds
backup_lcp_speed_last_60sec integer Number of bytes written to disk by backup and LCP processes per second, averaged over the last 60 seconds
redo_speed_last_60sec integer Number of bytes written to REDO log per second, averaged over the last 10 seconds
std_dev_backup_lcp_speed_last_60sec integer Standard deviation in number of bytes written to disk by backup and LCP processes per second, averaged over the last 60 seconds
std_dev_redo_speed_last_60sec integer Standard deviation in number of bytes written to REDO log per second, averaged over the last 60 seconds
slowdowns_due_to_io_lag integer Number of seconds since last node start that disk writes were slowed due to REDO log I/O lag
slowdowns_due_to_high_cpu integer Number of seconds since last node start that disk writes were slowed due to high CPU usage
disk_write_speed_set_to_min integer Number of seconds since last node start that disk write speed was set to minimum
current_target_disk_write_speed integer Actual speed of disk writes per LDM thread (aggregated)

Prior to NDB 7.4.3, the standard deviation used in obtaining the values shown in the std_dev_backup_lcp_speed_last_10sec, std_dev_redo_speed_last_10sec, std_dev_backup_lcp_speed_last_60sec, and std_dev_redo_speed_last_60sec columns of this table was not calculated correctly. (Bug #74317, Bug #19795072)

Prior to NDB 7.4.3, some columns of this table showed values in kilobytes or other multiples of bytes. In NDB 7.4.3 and later, all such columns display values in bytes. (Bug #74317, Bug #19795072) The following table provides information about disk_write_speed_aggregate as implemented previously.

Table 18.351 Columns of the disk_write_speed_aggregate table in NDB 7.4.2 and earlier

Column Name Type Description
node_id integer Node ID of this node
thr_no integer Thread ID of this LDM thread
backup_lcp_speed_last_sec integer Number of kilobytes written to disk by backup and LCP processes in the last second
redo_speed_last_sec integer Number of kilobytes written to REDO log in the last second
backup_lcp_speed_last_10sec integer Number of kilobytes written to disk by backup and LCP processes per second, averaged over the last 10 seconds
redo_speed_last_10sec integer Number of kilobytes written to REDO log per second, averaged over the last 10 seconds
std_dev_backup_lcp_speed_last_10sec integer Standard deviation in number of kilobytes written to disk by backup and LCP processes per second, averaged over the last 10 seconds
std_dev_redo_speed_last_10sec integer Standard deviation in number of kilobytes written to REDO log per second, averaged over the last 10 seconds
backup_lcp_speed_last_60sec integer Number of kilobytes written to disk by backup and LCP processes per second, averaged over the last 60 seconds
redo_speed_last_60sec integer Number of kilobytes written to REDO log per second, averaged over the last 10 seconds
std_dev_backup_lcp_speed_last_60sec integer Standard deviation in number of kilobytes written to disk by backup and LCP processes per second, averaged over the last 60 seconds
std_dev_redo_speed_last_60sec integer Standard deviation in number of kilobytes written to REDO log per second, averaged over the last 60 seconds
slowdowns_due_to_io_lag integer Number of seconds since last node start that disk writes were slowed due to REDO log I/O lag
slowdowns_due_to_high_cpu integer Number of seconds since last node start that disk writes were slowed due to high CPU usage
disk_write_speed_set_to_min integer Number of seconds since last node start that disk write speed was set to minimum
current_target_disk_write_speed integer Actual speed of disk writes per LDM thread (aggregated)

The disk_write_speed_aggregate table was added in NDB 7.4.1.


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