Teradata Workload Management comes in two versions: Teradata Integrated Workload Management (TIWM) which includes basic functionality, and Teradata Active System Management (TASM) which has a richer set of capabilities. Both TIWM and TASM come with several system-defined workloads. This blog explains what these workloads are, why they are there, and whether you can ignore them or not.
Timeshare Default Workloads
There are four Timeshare workloads that automatically come with every TIWM and TASM system. They are T-WD in Timeshare Top, H-WD in Timeshare High, M-WD in Timeshare Medium and L-WD in Timeshare Low. You can view them from the Workload Distribution screen of Viewpoint Workload Designer, as shown below.
The purpose of these workloads is backwards compatibility with workload management before SLES 11. Prior to SLES 11, customers could use the leading characters of an account string to classify to a priority. For sites without TASM, account strings were the method of directing a request to one of the priorities in SLES 10. For example, if the account string for a user who submits a request begins with ‘$L’ then SLES 10 priority scheduler would automatically link that request to a performance group named “Low”.
Because some users were relying on the information carried in account strings to point to priorities at the time they upgraded from SLES 10 to SLES 11, keeping those conventions in place was seen as a way to ease the transition into SLES 11. It meant that things would work in a similar fashion after the upgrade to SLES 11 and gave the administrator time to evaluate and setup the new SLES 11 workloads with stronger, more diverse classification capabilities.
You can see the classification criteria that is currently in place for these default Timeshare workloads by looking at the Workload Evaluation screen. Note the old convention of ‘$H’ is still being used.
Timeshare Default Workloads Today
If you are starting off on a Teradata system at the SLES 11 operating system level, or if you have migrated from SLES 10 years ago, then you probably don’t have to be concerned with these default Timeshare workloads. Most sites simply ignore them. You can delete them if you wish, just to get them out of the way. To delete them, go to the main Workload screen, click on the down arrow to the left of the workload name, and you will see an option to delete. Select that option and hit SAVE and the workload will be removed.
Before you delete these Timeshare workloads, make sure to validate that no requests are mapping to them.
The Default Workload
While it’s not a bad idea to delete the default Timeshare workloads if they are not being used, there is one workload you definitely do not want to delete, and that’s the single default workload WD-Default. In fact Viewpoint will not let you delete it. WD-Default is there to be the catch-all for any request that didn’t classify to any other workload. It ensures that all request run.
If you look at the evaluation order screen shown above, you will see that WD-Default is at the bottom of the evaluation order. This is by intent. Always make sure this convention is continued. Notice on that screen that WD-Default has no classification criteria. If you were to place WD-Default at the top of the evaluation order, all requests would classify to it. So make sure it remains at the bottom, always, forever.
WD-Default is placed in Timeshare Medium. You can move WD-Default to another Timeshare access level, but you cannot move it out of Timeshare. Usually there is no requirement to move it, since the goal is not to have any work running there.
It’s a good idea to keep on eye on whether or not work is running in WD-Default. If you see resource consumption taking place there then drill down on what is running there and make sure all your classification rules are valid, and that all entering work is classifying to a workload that you have defined.
Note that console utilities, such as ScanDisk and CheckTable, map to WD-Default by default. However most sites change that mapping to be one of the standard Timeshare workloads.
It is recommended that sites not purposefully allow anything to run in WD-Default. The main reason for this is so you know if something is falling through your classification rules. If you find that to be the case you know something different is happening and that it needs to be addressed.
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