Checkpoints (k)

Checkpoints (k)

This panel shows detailed information on the last x checkpoints, where x is 8 for older versions of Progress and 32 for 11.7+. Also, as of 11.7, the number of checkpoint statistics in memory is configurable via the -numcheckpointstats startup parameter.

ProTop RT Label Alertable Metric* Description
Chkpt# N/A Checkpoint Number
Cluster N/A BI file cluster number of the checkpoint
Start N/A Start date and time of the checkpoint
Finish N/A End time of the checkpoint
Length N/A Length of time of the checkpoint
  zcpLenSec This alertable field is not displayed and contains the length of the ckpt in seconds
Dirty dirty Number of dirty buffers associated with the checkpoint
ChkptQ cptq Number of buffers in the checkpoint queue
Scan scan Number of buffers scanned by APWs during the checkpoint
APW Q apwq Number of buffers in the APW queue
Flushed flush The number of buffers written to disk at the end of the checkpoint. See below
Duration duration Duration of the chekcpoint
Synch Time syncTime Time to write modified database files to disk at the end of a checkpoint
BI Wr biWrt Number of writes to the BI file
BIWrTm biWrtTm Amount of time spent writing to the BI file
DBWr DBWrt Writes to the database
DBWrTm DBWrtTm Amount of time spent writing to the database

*Requires data collector "Checkpoints" in pt3agent.cfg. With the commercial version of ProTop, you can configure alerts using the metric names in this column. For a full list of metrics, see the Alertable Metrics section.

Buffers Flushed Insight

At the end of a checkpoint, if there are still buffers remaining in the checkpoint queue not written to disk, the DB halts all forward processing until the remaining "flushed" buffers are written to disk. This value should always be 0.

There are three basic ways to respond to this problem:

  1. Improve your disk write performance. See the syncIO metric on the dashboard page
  2. Add more APWs
  3. Increase the BI cluster size

The first is the hardest to do, sincce infrastructure changes can be challenging and are often out of the control of the OpenEdge DBA.

The second is rarely the answer except on databases that do a huge number of writes. If you think you need more APWs, I'd challenge you to contact us first.

Increasing BI cluster size is the usual answer, especially if it's less than 16 MB. Note that the maximum BI cluster size is 256 MB.