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SAP HANA Database Server Management Console (hdbcons) Interview Question and answer

25 Jan 2016 11:25 am || 0

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>]
  • Per default hdbcons will connect to the indexserver process, but you can specify the process ID of another SAP HANA process via "-p <pid>" or the name of another SAP HANA process via "-e <process_name>" (e.g. <process_name> = 'hdbnameserver').
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
  • 1827393
  • 1999020
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>
  • 1786918
  • 1999997
Generate output file with allocator stack trace information for heap allocator <allocator>
mm f <allocator> as
  • 1786918
  • 1999997
Activation of allocator call stack trace for <allocator>
mm f <allocator> as -d
  • 1786918
  • 1999997
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
  • 2063657
  • 2086024
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>
  • 1999880
  • 2100009
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]
  • 1889081
  • 2107959
  • 2127458
Persist preload information based on columns currently loaded in memory ('-s' for synchronous write)

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