The benefit of segregating user groups by line-of-business (using logon
groups) is related to the point that groups of users (like SD users or HR users,
for example) tend to use the same sets of data. They (generally) work with the
same groups of tables and hit the same indexes using the same programs
(transactions).
So, if you can group all of the users hitting the same tables, onto (or one
set of) App server(s), then you can tune the App server buffers to a much
greater extent. If the FI users (generally) never hit against the HR tables
then the App servers in the FI group don't (generally) have to buffer any HR
data. That leaves you free to make memory and buffer adjustments to a more
drastic extent, because you don't have to worry (as much) about screwing the HR
users (as an example), when you're adjusting the FI server group.
So, (in opinion only) you should start with a buffer hit ratio analysis / DB
table & index access analysis (by user group) to see where you would get the
best benefit from this kind of setup. If you don't have this kind of info, then
creating logon groups by line-of-business may have no benefit (or worst case,
may make performance degrade for the group with the highest load %). You need
some historical information to base your decision on, for how to best split the
users up.
You may find that 50% of the load is from the SD users and so you may need
one group for them (with 3 App servers in it) and one other group for everyone
else (with the other 3).
The logon group(s) will have to be referenced by SAP GUI, so SAP GUI (or
saplogon.ini + maybe the services file, only) will have to change to accomodate
any new groups you create in SMLG. Also consider that there's variables for
time-of-day (load varies by time-of-day) and op-mode switches (resources vary by
op-mode).
All Work process are running? What will be our action?
Are all the work processes (dia,btc,enq,upd,up2,spo) running or just all the
dialog work processes?
If all the work processes are running, then you may want to look at SM12 (or
is SM13?) and see if updates are disabled. If they are, look at the alert log
(if it's an Oracle database) and see if you have any space related errors (e.g.
ORA-01653 or ORA-01654). If you do, add a datafile or raw device file to the
applicable tablespace and then, re-enable updates in SM12.
If only all the dialog work processes are running, there are several possible
causes. First, look to see if there's a number in the Semaphore column in SM50
or dpmon. If there is, click once on one of the numbers in the Semaphore column
to select it and then, press F1 (help) to get a list of Semaphores. Then,
search OSS notes and, hopefully, you'll find a note that will tell you how to
fix the problem.
If it's not a semaphore (or sometimes if it is), use vmstat on UNIX or task
manager on Windows to see if the operating system is running short on memory
which would cause it to swap. In vmstat, the free column (which is in 4k pages
on most UNIX derivatives) will be consistently 5MB or so and the pi and/or po
columns will have a non- zero value. The %idle column in the cpu or proc
section will be 0 or a very low single digit while the sys column will be a very
high double-digit number because the operating system is having to swap programs
out to disk and in from disk before it can execute them.
In task manager, look at free memory in the physical memory section under the
performance tab. If it's 10MB or 15MB (I think), then the operating system will
be swapping.
Usually, when all the dialog work processes are running, you won't be able to
log in via SAPgui and will need to execute the dpmon utility at the commandline
level. The procedure is basically the same on UNIX and Windows.
On UNIX:
telnet to server and login as sidadm user.
cd to /sapmnt/SID/profile directory
execute "dpmon pf=SID_hostname_SYSNR" (e.g. PRD_hercules_DVEGMS00) select option
"m" and then, option "l"
On Windows:
Click on START, then RUN
Type "cmd" and press enter
change to drive where profile directory resides (e.g. f:)
cd to \sapmnt\SID\profile
execute "dpmon pf=SID_hostname_SYSNR" (e.g. PRD_zeus_DVEGMS00) select option "m"
and then, option "l"
On both operating systems, you'll see a screen that looks like what you see
in SM50. Depending on what you see here, will depend on what you do next, but
checking the developer trace files (e.g. dev_disp) in the work directory (e.g.
/usr/sap/SID/DVEGMS00/work) is never a bad idea.
