| Moab Workload Manager® |
Appendix D: Adjusting Default Limits
Moab is distributed in a configuration capable of supporting multiple architectures and systems ranging from a few processors to several thousand processors. However, in spite of its flexibility, for performance reasons, it still contains a number of default object limits parameters and static structures defined in header files. These limits constrain such things as the maximum number of jobs, reservations, and nodes that Moab can handle and are set to values that provide a reasonable compromise between capability and memory consumption for most sites. However, many site administrators want to increase some of these settings to extend functionality, or decrease them to save consumed memory. The most common parameters are listed in what follows and can be adjusted by simply modifying the moab.cfg configuration file or by adjusting the appropriate #define and rebuilding Moab.
| Parameter | Location | Default | Max Tested | Description |
| JOBMAXNODECOUNT | moab.cfg (dynamic parameter) | 1024 | 8192 | Maximum number of compute nodes that can be allocated to a job. (Can also be specified within configure using --with-maxjobsize=<NODECOUNT>.) |
| MAXJOB | moab.cfg (dynamic parameter) | 4096 | 50000 | Maximum number of jobs that can be evaluated simultaneously. (Can also be specified within configure using --with-maxjobs=<JOBCOUNT>.) |
| MAXRSVPERNODE | moab.cfg (dynamic parameter) | 24 | 1024 | Maximum number of reservations a node can simultaneously support. |
| MMAX_ACCT | moab.h | 1024 | 128 | Total number of accounts allowed. |
| MMAX_ATTR | moab.h | 128 | 512 | Total number of distinct node attributes (PBS node attributes/LL node features) that can be tracked. |
| MMAX_CLASS | moab.h | 24 | 64 | Total number of distinct job classes/queues available. |
| MMAX_CLIENT | moab.h | 128 | 128 | Total number of simultaneous client connections allowed. |
| MMAX_FSDEPTH | moab.h | 24 | 32 | Number of active fairshare windows. |
| MMAX_GRES | moab.h | 8 | 300 | Total number of distinct generic resources that can be tracked. NOTE: MMAX_ATTR must be greater than or equal to MMAX_GRES. |
| MMAX_NODE | moab.h | 5120 | 160000 | Maximum number of compute nodes supported. (Can be specified within configure using --with-maxnodes=<NODECOUNT>.) |
| MMAX_PAR | moab.h | 4 | 32 | Maximum number of partitions supported. |
| MMAX_QOS | moab.h | 128 | 128 | Total number of distinct QoS objects available to jobs. |
| MMAX_RACK | moab.h | 200 | 200 | Total number of distinct rack objects available within cluster. |
| MMAX_RANGE | moab.h | 256 | 1500 | Total number of distinct timeframes evaluated. NOTE: This is proportional to the size of the cluster and the number of simultaneously active jobs in the cluster. (Can be specified within configure using --with-maxrange=<RANGECOUNT>.) Increasing this value will not increase the size of total memory consumed by Moab but may result in minor slowdowns in the evaluation and optimization of reservations. |
| MMAX_RSV | moab.h | 1024 | 8192 | Total number of distinct reservations allowed per cluster. (Can be specified within configure using --with-maxrsv=<RSVCOUNT>.) |
| MMAX_SRSV | moab.h | 128 | 256 | Total number of distinct standing reservations available. |
| MMAX_TASK | moab.h | 4096 | 16000 | Total number of tasks allowed per job. (Can be specified within configure using --with-maxtasks=<TASKCOUNT>.) |
| MMAX_GTRIG | moab.h | 2048 | 2048 | Total number of system-wide triggers. (Can be specified within configure using --with-maxtriggers=<TRIGGERCOUNT>.) |
| MMAX_TRIG | moab.h | 24 | 24 | Total number of triggers allowed per object. (Can be specified within configure using --with-maxobjtriggers=<TRIGGERCOUNT>.) NOTE: MMAX_GTRIG must be greater than or equal to MMAX_TRIG. |
Moab currently possesses hooks to allow sites to create local algorithms for handling site specific needs in several areas. The contrib directory contains a number of sample local algorithms for various purposes. The MLocal.c module incorporates the algorithm of interest into the main code. The following scheduling areas are currently handled via the MLocal.c hooks.
- Local Job Attributes
- Local Node Allocation Policies
- Local Job Priorities
- Local Fairness Policies
See Also