OBIEE Systems Management – dodgy counter behaviour

Over the last few months I’ve been doing a lot of exploring of OBIEE Systems Management data, covered in a mini-series of blog posts, Collecting OBIEE systems management data.

There are a vast number of counters exposed, ranging from the very interesting (Active Sessions, Cache Hits, etc) to the less so (Total Query Piggybacks, although for some seriously hardcore performance tuning even this may be of interest).

This short blog post is about a couple of counters which I’ve been monitoring but which looks to not be entirely reliable. Both are in the Oracle BI DB Connection Pool, and are:

• Current Connection Count – The current number of open connections in the thread pool.
• Current Busy Connection Count – The current number of connections assigned to process a query or processing a query in the DB Connection pool.

A picture tells a thousand words in this case:

OBIEE Connection Pool data

We can clearly see :

• Current Busy Connection Count (“The current number of connections assigned to process a query or processing a query in the DB Connection pool.“) goes negative!
• Current Connection Count (“The current number of open connections in the thread pool.“) accumulates. Either the counter is buggy, or there really are thousands of open connections in the thread pool which sounds worrying in itself.

These two counters reset and correct themselves only on a BI Server restart, which can be seen by the red vertical lines on the graph.

A snapshot of the current figures (via JConsole) backs up these numbers and puts “Current Connection Count” in context next to the ‘Peak’ and ‘Accumulated’ figures:

OBIEE Systems Management data, viewed through JConsole

Collecting OBIEE systems management data with jmx

Introduction

This is the first part of three detailed articles making up a mini-series about OBIEE monitoring. It demonstrates how to capture OBIEE performance information, and optionally graph it out and serve it through an auto-updating webpage.

For some background on OBIEE’s Systems Management component, along with JMX and MBeans, see here and here. The following assumes you know your mbeans from coffee beans and jmx from a bmx.

The metric collection is built around the jmxsh tool. This is similar to jmxterm and both provide command-line access to jmx. Once it’s commandline, it’s scriptable 🙂

This was developed and works on both Windows (through cygwin) and HP-UX.

The Script

jmxsh uses the a scripting language based on tcl, and with a bit of trial-and-error I developed the following script, obieejmx.tcl. It connects to a remote BI server, authenticates to the JMX agent, and then periodically polls the jmx counters and writes the values to a tab-separated file. It runs until you cancel it.

# obieejmx.tcl
# OBIEE JMX collector
# https://rnm1978.wordpress.com
#

# Set connection details
set host my-remote-server
set port 9980
set user jmx-user-name
set pw my-jmx-password

# Define the counters (userdefined ID / MBean / Attribute list, tab separated)
set mbeanattrs [list]
lappend mbeanattrs {1   Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Connection Pool      Current Open Connections}
lappend mbeanattrs {2   Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Query Cache  Current Running Queries}
lappend mbeanattrs {3   Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Query Cache  Current Cache Entries}
lappend mbeanattrs {4   Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Sessions     Active Sessions}
lappend mbeanattrs {5   Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Sessions     Current Sessions}
lappend mbeanattrs {6   Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Sessions     Sessions Logged On}
lappend mbeanattrs {7   Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI DB Connection Pool,name=Star_Oracle Data Warehouse_Oracle Data Warehouse Connection Pool     Current Busy Connection Count}
lappend mbeanattrs {8   Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI DB Connection Pool,name=Star_Oracle Data Warehouse_Oracle Data Warehouse Connection Pool     Current Connection Count}
lappend mbeanattrs {9   Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI Physical DB,name=Oracle Data Warehouse       KiloBytes/sec}
lappend mbeanattrs {10  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI Physical DB,name=Oracle Data Warehouse       Queries/sec}
lappend mbeanattrs {11  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI Physical DB,name=Oracle Data Warehouse       Rows/sec}
lappend mbeanattrs {12  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,name=Oracle BI General      Active Execute Requests}
lappend mbeanattrs {13  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,name=Oracle BI General      Active Fetch Requests}
lappend mbeanattrs {14  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,name=Oracle BI General      Avg. query elapsed time}
lappend mbeanattrs {15  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,name=Oracle BI General      Queries/sec}
lappend mbeanattrs {16  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,name=Oracle BI General      Total sessions}
lappend mbeanattrs {17  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,name=Oracle BI General      Succeeded Logins Ratio as %}

# Write the header
puts -nonewline "Timestamp"
foreach {mbeanattr} $mbeanattrs {
        # Get the mbean & attribute
        set parts [split $mbeanattr "\t"]
        set mbean [lindex $parts 1]
        set attr [lindex $parts 2]
        puts -nonewline "\t$mbean $attr"
}
puts ""

# Connect to the host
jmx_connect -h $host -p $port -U $user -P $pw

# Get the values
while {0 == 0} {
        puts -nonewline "[clock format [clock seconds] -format %Y-%m-%d-%H:%M:%S]"
        foreach {mbeanattr} $mbeanattrs {
                # Get the mbean & attribute
                set parts [split $mbeanattr "\t"]
                set mbean [lindex $parts 1]
                set attr [lindex $parts 2]

                #Uncomment for debug:
                #puts "---"
                #puts "$mbean $attr"

                # Get the metric and write to output
                puts -nonewline "\t[ jmx_get -m $mbean $attr]"

        }
        # Flush the output buffer line
        puts ""
        # Sleep for 60 seconds
        after 60000
}

You may want to tweak the polling frequency, depending on the metrics that you’re collecting and the purpose of them. For building up a general picture of system usage (active sessions, etc), then every minute – or greater – should be sufficient. For other metrics which record rates per second (eg “New Sessions / sec”) then you may well want to sample more frequently.

You invoke this via jmxsh (download link) using the following syntax:

$java -jar jmxsh-R5.jar obieejmx.tcl

or if you’ve setup the (ambiguously-named) file jmxsh, you can use this:

$./jmxsh obieejmx.tcl

It will write the counter values to stdout, so capture it to file using

./jmxsh obieejmx.tcl >> results.jmx 

To run it continually as a background process, use nohup (so it doesn’t die when you logoff) and & (to run it in the background):

# Run collector indefinitely
nohup ./jmxsh obieejmx.tcl >> results.jmx &

The output you’ll get will look like this:

2010-11-29-14:41:17     5       0       38      1       12      9       0       614     0       0       0       0       0       0       0       3       0
2010-11-29-14:42:17     5       0       33      1       12      9       0       614     0       0       0       0       0       0       0       3       0
2010-11-29-14:43:17     5       0       33      1       12      9       0       614     0       0       0       0       0       0       0       3       0
2010-11-29-14:44:17     5       0       33      1       12      9       0       614     0       0       0       0       0       0       0       3       0

To stop the collector running, you’ll need to find the process

$ps -ef|jmxsh 
userid 14695     1  2  Nov 29  ?         5:12 /opt/java6/bin/IA64N/java -jar ./jmxsh-R5.jar obieejmx.tcl

and then kill it

kill 14695

Defining the counters

You’ll have noticed in my script that I define an array of counter names. You can get a list of all the counters in various ways including through Presentation Services (saw.dll?perfmon), OAS/OC4J, or JConsole. My personal preference is using Presentation Services (saw.dll?perfmon) as it gives the list nice and neatly and with an explanation of each counter.
Once you’ve decided which you want to collect, you need to use jmxsh again to get the correct format. Counters are defined as Attributes (eg Current Open Connections) within MBeans (eg Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Connection Pool). Different jmx interfaces seem to label the MBean in a different format, for example:

jmxsh:  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Sessions
jmxterm:Oracle BI Management:AppName=Oracle BI Presentation Server,Oracle BI=Performance,name=Oracle BI PS Sessions

(spot the order in which “Oracle BI=” and “AppName=” are listed)
So for using jmxsh in your script, use jmxsh to get the exact MBean names otherwise you’ll spend a long time tearing your hair out wondering why it’s not working!
To get jmxsh to list the MBeans, you use it in the ‘browse’ mode. First off, run jmxsh and connect to your OBIEE server using the jmx_connect command

$ java -jar jmxsh-R5.jar
jmxsh v1.0, Tue Jan 22 16:23:12 GMT 2008


Type 'help' for help.  Give the option '-?' to any command
for usage help.


Starting up in shell mode.
% jmx_connect -h myserver -p 9980 -U myjmxuser
Password: ********
Connected to service:jmx:rmi:///jndi/rmi://myserver:9980/jmxrmi.

Hit enter at this point and it’ll switch to browse mode, and list out the MBean Domains.

%
Entering browse mode.
====================================================


 Available Domains:


       1. java.util.logging
       2. JMImplementation
       3. Oracle BI Management
       4. java.lang


  SERVER: service:jmx:rmi:///jndi/rmi://myserver:9980/jmxrmi

Select Oracle BI Management

====================================================
Select a domain: 3
====================================================

This lists all the MBeans within Oracle BI Management – there’s a lot!

 Available MBeans:


       1. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Chart Engine
       2. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI DB Connection Pool,name=Star_Oracle Data Warehouse_Oracle Data Warehouse Writeback Connection Pool
       3. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,type=Oracle BI PS Thread Pools,name=TaskScheduler
       4. Oracle BI Management:Oracle BI=Configuration,type=Presentation Server Configuration,name=Query
       5. Oracle BI Management:Oracle BI=Configuration,type=Presentation Server Configuration,name=AsyncLogon[ThreadPoolDefaults]
       6. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Query Cache
[...]
     134. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Sessions
[...]

You can filter by defining a glob filter by typing your search term at the “Select an mbean:” prompt. For example:

====================================================
Select an mbean: Performance
====================================================

 Available MBeans:

       1. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Chart Engine
       2. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI DB Connection Pool,name=Star_Oracle Data Warehouse_Oracle Data Ware
house Writeback Connection Pool
       3. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,type=Oracle BI PS Thread Pools,name=TaskScheduler
       4. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Query Cache
[...]
      53. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI Generic Cache,name=Star_DrillDownQuery_Cache

  SERVER: service:jmx:rmi:///jndi/rmi://myserver:9980/jmxrmi
  DOMAIN: Oracle BI Management
  GLOB:   *Performance* (space to clear)

This shows just MBeans with Performance in the name. Alternatively use a wildcard within the glob:

Select an mbean: Performance*Cache
====================================================

 Available MBeans:

       1. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Query Cache
       2. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Catalog XML Cache
       3. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI Generic Cache,name=Star_DrillDownInfo_Cache
       4. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Security Manager Account Cache
       5. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI Generic Cache,name=Star_LDAP_Cache
       6. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Catalog Attribute Cache
       7. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Security Manager Account Memberships Cache
       8. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI Generic Cache,name=Star_Plan_Cache
       9. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI Generic Cache,name=Star_ColumnAggrInfo_Cache
      10. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI Generic Cache,name=Star_RowWiseInit_Cache
      11. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS DXE Cache
      12. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Cube Cache
      13. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,name=Oracle BI Data Cache
      14. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS XML Document Caches
      15. Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Server,type=Oracle BI Generic Cache,name=Star_DrillDownQuery_Cache

  SERVER: service:jmx:rmi:///jndi/rmi://myserver:9980/jmxrmi
  DOMAIN: Oracle BI Management
  GLOB:   *Performance.*Cache* (space to clear)

If you use globs, remember to clear them by typing space and then enter, otherwise when you list Attributes you won’t see any which don’t also match your filter.

To view the Attributes for an MBean, enter the MBean’s number:

====================================================
Select an mbean: 134
====================================================

 Attribute List:

       1. -r- Integer     Current Sessions
       2. -r- Integer     Maximum Sessions
       3. -r- Integer     Sessions Logged On
       4. -r- Integer     Maximum Logged On
       5. -r- Integer     Current Embryonic Sessions
       6. -r- Integer     Maximum Embryonic Sessions
       7. -r- Integer     Active Sessions
       8. -r- Integer     Maximum Active Sessions
       9. -r- Integer     Total Lifetime Sessions
      10. -r- Integer     New Sessions / sec
      11. -r- Integer     Total Failed Logons
      12. -r- Integer     Failed Logons/sec
      13. -r- Integer     Total Logons
      14. -r- Integer     New Logons/Sec


  SERVER: service:jmx:rmi:///jndi/rmi://myserver:9980/jmxrmi
  DOMAIN: Oracle BI Management
  MBEAN:  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Sessions

Once you’ve chosen your MBeans and Attributes, you can incorporate them into the obieejmx.tcl script by adding additional lappend lines. The format is:

lappend mbeanattrs {<ID><tab><mbean><tab><attribute>}

ID is just a number used later on in the process, it can be whatever you like. Make sure the three values are tab-separated.
An example line is:

lappend mbeanattrs {17  Oracle BI Management:Oracle BI=Performance,AppName=Oracle BI Presentation Server,name=Oracle BI PS Sessions      Current Embryonic Sessions}

If you get the error “Cannot convert result to a string” then check your MBean and Attribute names, normally this error means it can’t find what you’ve asked for. Also check that the array member definitions (lappend) are tab separated, not just space separated.

Where next?

Now you’ve got the data, do something with it! See charting OBIEE performance data with gnuplot.

OBIEE monitoring

Those of you who read my blog regularly may have noticed I have a slight obsession with the OBIEE systems management capability which is exposed through JMX. Venkat has blogged this week about JMX in OBI11g, and it’s clearly a technology worth understanding properly.
I’ve recently been tinkering with how to make use of it for monitoring purposes, most recently using JConsole and discussed here. What follows is an extension of this idea, cobbled together with a bit of shell scripting, awk, gnuplot, and sticky backed plastic. It’s built on OBIEE 10g – for OBI11g it may differ (although I understand that Performance MBeans still exist).

Whether you collect metrics for day-to-day monitoring of OBIEE, capacity planning, or investigative work, it’s valuable data (in my humble opinion) that will help you understand the usage of the application by the users that you support.

To whet your appetite, here’s a sample of what you can produce, in realtime:

Performance metrics from a two-server OBIEE cluster

Performance data related to Sessions in BI and Presentation Services

Before you start this, I recommend reading how to secure your jmx agent if you’re working with production systems.

Overview

There are three parts to my monitoring application, and you can pretty much pick and mix as you want. Obviously without any data collected then graphing it will be pretty dull, but you may opt to collect the data and then work with it another way (Excel, OBIEE, etc).
I’ve broken the details down into three separate blog posts:

1. Metric collection from a remote BI Server, using jmxsh
2. Graph rendering of the collected data, using gnuplot
3. Web page serving of the rendered graphs, bolted onto the OAS already in place for Presentation Services.

Oracle BI Management / Systems Management MBeans

Part of looking at the various gubbins inside OBIEE led me to realise that the Oracle BI Management application drives quite a few things. It exposes MBeans (Management Beans, a java term), accessible through jmx.
In the installation of OBIEE this component is referred to as “Systems Management”.

The MBeans give us real-time performance information, along with access to all the configuration options that are normally done through config files (instanceconfig.xml etc).
Bear in mind if using it for updating configuration instead of through the files you don’t get any backup created, so for that reason alone I would suggest it should only be used for reading current values.

They can be accessed directly through jconsole, a java GUI distributed with java jdks, or oc4j (Oracle Containers For Java) which you’ll either be running directly or as part of OAS.

@lex has details here about accessing through oc4j/OAS.
It’s worth noting if you have done separate BI Server and Presentation Services installations then on your PS server you’ll already have an application server running, but on your BI Server you might need to start oc4j (on unix: obiee/oc4j_bi/bin $nohup oc4j -start &)

The MBeans are used as a source for both perfmon and the BI Management Pack in EM.

jManage is an open-source tool that can also be used to access the MBeans:

See this post for information

OBIEE admin tools & hacks

As a kid I loved the idea of lego where you can disassemble and reassemble something from the ground up. As soon as I got my hands on a computer it was the same. You can have your Acorn Archimedes with its games, where do I find the sprites and sound files behind it? Likewise Microsoft Word, let me at the VBA underneath to hack it around and see what else it can do.

With that in mind I’ve enjoyed discovering bits of the “underbelly” of OBIEE from manuals, blogs and a few SRs I’ve raised.

Here’s my list so far, please feel free to add to it in the comments and correct any errors or missing credits 🙂

Oracle BI Management data
This server-based performance and diagnostic data can be access through several methods:

perfmon

Credit: http://obiee101.blogspot.com/2009/07/obiee-perfmon-performance-monitor.html

Go to http://%5Bserver%5D:%5Bport%5D/analytics/saw.dll?perfmon and you’ll get the Performance Monitor. This is the same data that’s used by the BI Management Pack and is accessible through the jmx agent

oc4j

An alternative to jconsole is to access the Oracle BI Management MBeans through oc4j. @lex has details here

Windows perfmon

More details in separate post here

jconsole

The same data as through perfmon above, full details here: jmx agent

jManage

jManage is an open-source tool that can also be used to access the MBeans:

See this post for information
sawping
Credit: http://tipsonobiee.blogspot.com/2009/07/sawping.html

C:\OracleBI\web\bin>sawping.exe -help
sawping [-p port] [-s host] [-v (verbose mode)] [-q (quiet mode)] [-h]C:\OracleBI\web\bin>sawping.exe -s myPSserver.company.net -v
Server alive and well

NB not got this working yet on unix:

obiee/web/bin64 $./sawping64
/usr/lib/hpux64/dld.so: Unable to find library ‘libsawcomm643r.so’.

Found in [OracleBI Home]/web/bin (or Bin64)

nqcmd
Great little command line tool. We’re using it for some crude load testing (get a bunch of logical-SQL statements and use unix scripting to fire them in parallel at the BI Server) as well as monitoring of the BI Server (“pinging” it regularly with some small logical-SQL to make sure it responds correctly)
Found in [OracleBI Home]/server/Bin (or Bin64)

UnixChk
(UNIX only, duh)
What it says on the tin – validates your Unix environment is suitable for OBIEE

Usage: UnixChk.sh [-b] [-s | ]

diagcap
Support asked me to run this, you’ll find it in [OBIEE home]/server/Bin

Usage: ./diagcap.sh -d [-p] [-h]
-d : directory that info will be stored
The directory must be empty
-p : absolute path to Oracle BI root directory
May be omitted if the SAROOTDIR
environment variable is set
-h : show this help message

It collects all the config files and log files from your environment into a TAR archive, which you can then send to support.

tusc
Not OBIEE as such, but interesting for the truly nosy. This is a unix (HP) tool which you use to invoke a program and then get low-level diagnostics on what it’s up to. Most of the output may be gobbledegook to all but the hardcore programmer, but it does sometimes pick out if a library file is missing etc.
For example to invoke nqqserver in run-sa.sh:

tusc -vfe ${ANA_BIN_DIR}/nqsserver 2>&1 &

Administration Tool
Maybe not so unknown, but has front-end for monitoring clusters which I liked

The AdminTool can also be fed a script via the command line, see details here

Other stuff
This is a list of binaries that might or might not be of interest and that I plan to have a play with at some point

NB obiee/setup/sa-init64.sh and common.sh scripts might need running first to set the environment variables correctly.

obiee/web/bin

• cryptotools – used for generating keys for authentication between obiee/delivers/xmlp
• sawmigrate – for migrating from older versions of OBIEE?

obiee/server/Bin

• equalizerpds – For equalising RPDs prior to merging as part of an upgrade process Reference
• ErrorMsgCheck (directory) – not sure
• nqerrormsgcompiler – not sure

$nqerrormsgcompiler
ErrorMessageCompiler [] []
Exiting

• nqlogviewer – For parsing BI server logs. Can be useful for clustered instances?
• nqschangepassword – For changing of RPD user passwords
• nqscripthostexec – not sure

$nqscripthostexec
Usage: nqscripthostexec Memory fault(coredump)

• nqsshutdown – To shut down a BI Server via DSN reference (see here)
• nqsudmlcli – something to do with UDML?
• nqudmlexec – executing UDML against the RPD
• nqudmlgen – generating UDML from an RPD
• nqxudmlexec – executing XML formatted UDML against the RPD
• nqxudmlgen – generating XML formatted UDML from an RPD
• openssl – OpenSSL command line
• sametaexport – Oracle Database Metadata Generator. See Oracle Business Intelligence Server Administration Guide and Venkat’s blog
• saschinvoke – invoke Delivers jobs & iBots (see here)
• schconfig – Scheduler [Delivers] configuration program
• schshutdown – Shutdown Scheduler remotely?

In Googling these various binaries I found an excellent PDF from Andreas Nobbmann’s presentation in Brighton earlier this year: Scripting OBIEE – Is UDML and XML all you need?

Another useful page is here: http://gerardnico.com/wiki/dat/obiee/executable_files/start