collectl - Exception Reporting

# Exception Reporting

By default, collectl always reports all data for all devices. However, in the cases where there are dozens or possibly hundreds of devices such as with large disk farms, it may be desirable to only look at those devices that are actually doing something of interest. These are referred to as exceptions, because their activity has crossed a level of minimal activity. The defaults for these levels can be displayed with the -V switch or changed to different values with the -l switch. To change one or more values simply specify them as a string. There are currently 4 levels one can set:

- SVC - Disk Service Time
- IOS - Number of Disk I/O Operations
- LusKBS - Lustre KBytes/Sec
- LusReints - Lustre MDS Reint operations

Note that one can also specify all conditions must be met or simply 1 must be met by adding a selection of AND (the default) or OR, respectively.

For example, to set the minimal SVC level to 50 and require both SVC and IOS limits be reached, simply add the switch -l SVC:50. To change both values and require only 1 be met, separate them with a hyphen and be sure to include OR as one of the parameters such as -l SVC:50-IOS:10-OR, noting that order is not important.

One should not confuse exceptions which are based on threshold values, with filters which are based on the presence of explicit field values.

updated Feb 21, 2011