Systems Manual

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======HPC Cluster Monitoring======


====Ganglia====

On HPC systems the popular [[http://ganglia.sourceforge.net/|Ganglia monitoring tool]] is available. To bring up the Ganglia interface simply enter:
<code>
http://localhost/ganglia/
</code>

In Firefox (or any other browser that is installed on the system). The default screen is shown below.

{{ :wiki:ganglia-main.png?600 |}}

Clicking on the ''Limulus OHPC Cluster'' in the ''Choose a Source'' drop-down menu will show the individual nodes in the cluster. The ''load_one'' (one minute load) is displayed in total and for the individual nodes (shown below). 

{{ :wiki:ganglia-load1.png?600 |}}

Note that in addition to a myriad of other metrics it is possible to observe the CPU temperatures by selecting ''cpu_temp'' (as shown below).

{{ :wiki:ganglia-temps.png?600 |}}

More information on usage and configuration can be found at the [[http://ganglia.sourceforge.net/|Ganglia web site]].

====Warewulf Top (wwtop)====

Warewulf Top is a command line tool for monitoring the state of the cluster. Similar to the ''top'' command, ''wwtop'' is part of the Warewulf cluster provisioning and management system used on Limulus HPC systems. ''wwtop'' has been augmented to work directly with Limulus systems. Real-time CPU temperatures and frequencies are now reported. To run Warewulf Top enter:

  $ wwtop
  
The following screen will update in real time for nodes that are active (booted). 

{{ :wiki:wwtop-with-temps.png?600 |}}

Operation of the ''wwtop'' interface is described by the command help option shown below.

<code>
USAGE: /usr/bin/wwtop [options]
  About:
    wwtop is the Warewulf 'top' like monitor. It shows the nodes ordered by
    the highest utilization, and important statics about each node and
    general summary type data. This is an interactive curses based tool.

  Options:
   -h, --help       Show this banner
   -o, --one_pass   Perform one pass and halt

  Runtime Options:
    Filters (can also be used as command line options):
       i   Display only idle nodes
       d   Display only dead and non 'Ready' nodes
       f   Flush any current filters
    Commands:
       s   Sort by: nodename, CPU, memory, network utilization
       r   Reverse the sort order
       p   Pause the display
       q   Quit
    Views:
       You can use the page up, page down, home and end keys to scroll through
       multiple pages.

  This tool is part of the Warewulf cluster distribution
     http://warewulf.lbl.gov/
</code>

In addition to the temperature updates, ''wwtop'' now offers a new "one pass" option where a single report for all nodes is sent to the screen. This output is useful for grabbing snapshots of cluster activity. To provide a clean text output (no escape sequences) use the following command:

<code>
$ wwtop -o|sed "s,\x1B\[[0-9;]*[a-zA-Z],\n,g" |grep .
</code>

A report similar to the following will be written to the screen (or file as directed):

<code>
Cluster totals: 4 nodes, 24 cpus, 33 GHz, 77.84 GB mem
Avg:    0% cputil, 923.00 MB memutil, load 0.04, 251 procs, uptime   4 day(s)
High:   0% cputil, 2856.00 MB memutil, load 0.08, 523 procs, uptime  19 day(s)
Low:    0% cputil, 251.00 MB memutil, load 0.00, 148 procs, uptime   0 day(s)
Node status:    4 ready,    0 unavailable,    0 down,    0 unknown
Node name
  CPU  MEM SWAP    Up GHz  Temp    Arch Proc  Load  Net:KB/s Stats/Util
headnode    0%  17%   0%  19.1  12  38.0  x86_64  523  0.08        22 |        |
n0          0%   0%   0%   0.2   4  30.0  x86_64  158  0.04         0 |        |
n1          0%   1%   0%   0.0  13  33.8  x86_64  175  0.04         0 |  IDLE  |
n2          0%   1%   0%   0.0   4  28.0  x86_64  148  0.00         1 |        |

</code>

==== Slurm Top (slop)====

A real-time text-based Slurm "Top-like tool" called slop (SLurm tOP) is provided on all HPC Limulus systems. ''slop'' allows the batch queue and node status (similar to ''wwtop'' above) to be viewed from a text terminal. The screen will update every 20 seconds, but can be updated at any time by hitting the space bar. And example of the ''slop'' interface is shown below.

{{ :wiki:slop-main.png?600 |}}

The above example shows the Slurm batch queue in the top pane with job-ID partition, user, etc. The bottom pane displays the cluster nodes' metrics, similar to ''wwtop''. Pressing the ''h'' key will bring up the help menu (as shown below). Note: additional help with Slurm job states is also accessible by pressing the ''S'' key in the help menu.

<code>
Slop (SLurm tOP) displays node statistics and the batch queue on a cluster.

The top window is the batch queue and the bottom window are the hosts. The
windows update automatically and are scrollable with the arrow keys. A "+"
indicates that the list will scroll further. Available options:
  q - to quit userstat
  h - to get this help
  b - to make the batch window active
  n - to make the nodes window active
  spacebar - update windows (automatic update after 20 seconds)
  up_arrow - to move though the jobs or nodes window
  down_arrow - to move though the jobs or nodes window
  Pg Up/Down - move a whole page in the jobs or nodes window

Queue Window Commands:                  Host Window Commands:
  j - sort on job-ID                     s - sort on system hostname
  u - sort on user name                  a - redisplay all hosts
  p - sort on program name               return - top snapshot for node
  a - redisplay all jobs                 *nodename* means node is down
  d - delete a job from the queue
  return - display only the nodes for that job
  (When sorting on multiple parameters all matches are displayed.)

Press 'S' for Slurm Job State Help, or any other key to exit
</code>

A useful feature of ''slop'' is the the ability to "drill down" into job resources. For instance, if the cursor is placed on a job and then "Return" is pressed, only those nodes that are used by that particular job are displayed. In the following image, the node used for job 41622 is displayed in the lower pane. 

{{ :wiki:slop-node.png?600 |}}

If more specific node information is needed, a standard ''top'' snapshot is returned when the cursor is placed
on a node in the lower Host pane (switch to the host pane by entering "n") and entering "Return." A ''top'' snapshot for node ''n0'' (running job 41622 in the above image) is shown below. 

{{ :wiki:slop-top.png?600 |}}

For more information on ''slop'', consult the man page.

======Data Analytics Cluster Monitoring======

Data analytics systems (i.e. Hadoop/Spark/Kafka/etc.) are managed by [[ https://ambari.apache.org/|Apache Ambari]]. Ambari is a web-based management tool designed to make managing Hadoop clusters simpler. This includes provisioning, managing, and monitoring Apache Hadoop clusters (that often include tools like Spark, Kafka and others). Ambari provides an intuitive, easy-to-use Hadoop management web UI. An example of the Ambari dashboard is provided below. Basic Ambari usage is provided in the [[Using the Apache Ambari Cluster Manager|Using the Apache Ambari Cluster Manager]] section.

{{ :wiki:ambari-control-panel.png?600 |}}