FAQ HANA DB Server Management Console (hdbcons)
1. What is the SAP HANA database server management console?
The SAP HANA database server management console (hdbcons) is an expert tool delivered as part of the SAP HANA software. In normal cases, it is not required to use it, but in some scenarios, you can take advantage of its functionalities.
As improper usage of hdbcons can have a severe impact on SAP HANA, you should only run it under guidance of SAP (e.g. if recommended in a SAP incident or SAP Note).
2. How can hdbcons be started?
The following alternatives exist to start hdbcons:
| Tool | Details |
| Direct call (Linux level) | On Linux level you can start hdbcons via: hdbcons [-p <pid>] [-e <process_name>]
|
| SAP HANA Studio | Per default the database console isn't displayed, but you can change it via: Window -> Preference -> Global Settings -> Show Management Console for hdbcons Subsequently you will find an hdbcons input section at: Systems -> Administration -> Console |
| SQL | You can start hdbcons commands via SQL using: CALL MANAGEMENT_CONSOLE_PROC('<hdbcons_command>', '<host>:<port>', ?) <hdbcons_command> can contain any hdbcons command, e.g. the ones listed in "What are the most important hdbcons functionalities" below. |
3. Where do I find an overview of available hdbcons functionalities?
The following commands can be used in hdbcons to display an overview of hdbcons functionalities:
| Command | Details |
| hdbcons help | Overview of available server related options |
| hdbcons help <command> | |
| hdbcons -? | Overview of available client-related options |
4. What are the most important hdbcons functionalities?
The following table provides and overview about some hdbcons functionalities. Several of the 'mm' calls can be extended by the '-r' switch so that they apply also to sub-allocators of the specified heap allocator <allocator>.
snapshot a <snapshot_id>
| Command | Document | Details |
| context l -s |
|
Generate call stacks for active threads |
| crypto ssfs resetConsistency | 2097613 | Reset SSFS consistency |
| distribute e <host>:<port> <command> | 2146984 | Execute hdbcons command <command> on remote node identified via <host>:<port> |
| event acknowledge -t <type> | 2147247 | Acknowledge internal events of type <type> |
| help <command> | Provide further details for a specific hdbcons command <command> (e.g. 'mm') | |
| log backup | 2106240 |
Force log backup |
| log release | 1995412 | Release free log segments |
| mm bl -t <allocator> | 1999997 | List the top contributors to the memory allocation of a specific heap allocator <allocator> |
| mm cg -o <file>.dot <allocator> |
|
Generate output file with allocator stack trace information for heap allocator <allocator> |
| mm f <allocator> as |
|
Activation of allocator call stack trace for <allocator> |
| mm f <allocator> as -d |
|
Deactivation of allocator call stack trace for <allocator> |
| mm gc [-f] |
1999997 |
Return free memory to the operating system ('-f' to consider also free fragments in big blocks) |
| mm l -s -S -p | 1786918 | Print general heap allocator list with some statistics ('-s'), sorted by total size descending (-S) and peak usage statistics (-p) |
| mm ru | 1999997 | Reset all previous memory measurements ("reset usage") |
| mm top -l <num> <allocator> | 1999997 | Generate report with top <num> call stacks recorded for heap allocator <allocator> |
| page access a | 1999997 | Provide breakdown of Pool/PersistenceManager/PersistentSpace(0)/DefaultLPA/Page content based on page type |
| profiler clear | 1804811 | Reset kernel profiler trace |
| profiler print -o <file>.dot | 1813020 | Generate a kernel profiler trace output file <file>.dot |
| profiler start |
1813020 |
Start a kernel profiler trace |
| profiler stop | 1813020 | Stop a kernel profiler trace |
| replication i |
|
Overview of system replication information |
| resman minswappable -s 0 | 1970537 | Overwrite inadequate unload_lower_bound settings during recovery |
| resman s -s <size_gb>G | 2146989 | Shrink memory allocation to <size_gb> GB if possible |
| runtimedump dump | 1813020 | Generate a runtime dump |
| savepoint execute | 2228171 | Trigger a savepoint |
| 1999880 | Analyze SAP HANA snapshot (<snapshot_id> can be retrieved via "snapshot l") | |
| snapshot d <snapshot_id> |
|
Delete SAP HANA snapshot (<snapshot_id> can be retrieved via "snapshot l") |
| snapshot l | 1999880 | List SAP HANA snapshots |
| statreg print -n <monitor_view_name> | SAP HANA Troubleshooting Guide | Print content of monitor view <monitor_view_name> |
| tablepreload c [-f] | 2127458 | Print column preload information ('-f' for full information) |
| tablepreload w [-s] |
|
Persist preload information based on columns currently loaded in memory ('-s' for synchronous write) |
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