There is a new SAP Note https://websmp230.sap-ag.de/sap/support/notes/2007212 Tuning SAP Web Dispatcher and ICM for high load (Released on 30.12.2014)

which is really helpful, we used this for tuning of our sap portal

the note is also valid for The internal Web Dispatcher used by SAP HANA Extended Application Services (XS)

the note explains that (from 7.40 on), the sole parameter you need to set is parameter icm/max_conn to scale ICM

we used this note also for our older release (7.31), but variables are note supported in the profile here, so you have to manually compute the values:

# Example value for icm/max_conn

icm/max_conn = 2000

# Remaining parameters need not be touched

icm/req_queue_len = 6000

icm/min_threads = 10

icm/max_threads = 500

mpi/total_size_MB = (min(0.06 * $(icm/max_conn) + 50, 2000))

mpi/max_pipes = ($(icm/max_conn) * 2)

wdisp/HTTP/max_pooled_con = ($(icm/max_conn))

wdisp/HTTPS/max_pooled_con = ($(icm/max_conn))

important: please aware the operation system limit for max_conn:

ICM Windows 10000

ICM Linux, AIX, Solaris, HP-UX, AS/400 20000

SAP Web Dispatcher Windows, Linux 32000

SAP Web Dispatcher Solaris, HP-UX, AIX, AS/400, z/OS 16000

we sometimes faced timeouts and in the ‘dev_icm’  we see an error message:

*** ERROR => IcmConnPoolNewEntry: upper limit of desc in pool reached (used=500/max=500) 

in SAP MMC we could see the max_conn is not working/still was on 500:


our portal is running on windows, but we had set a max_conn value of 20000, as this is not possible on windows,

the ICM used default value of 500

so after we set icm/max_conn under the limit of 10000, in our case we used 6000, this worked fine.

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