Sybase 12.4.2 - Manual (Page 453)

CHAPTER 12 Managing System Resources
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-c The Catalog Store buffer cache is also the general memory pool for the Catalog
Store (the front end of Adaptive Server IQ). Sybase recommends a 64MB
minimum for 500 users.
Use of the -iqmt option is not required. If -iqmt is set too low for the number of
specified connections, the number of threads will be increased to handle the
number of requested connections. That is,
-gm overrides -iqmt . However, if the
number of IQ threads is elevated by means of the -iqmt option then that factor
needs to be used in setting limits, as described in "Setting Operating System
Parameters" below.
IQ Temp space
You may need to increase your temp dbspace to accommodate more users.
Relative priorities of new and existing connections
If Adaptive Server IQ is very busy handling already connected users, it maybe
slow to respond to new connection requests. In extreme cases (such as test
scripts that fire off hundreds of connections in a loop while the server is busy
with inserts) new connections may have to wait up to a minute to before
becoming active or may even time out their connection request. In this
situation, the server may appear to be down when it is merely very busy. A user
getting this behavior should try to connect again. This issue will be addressed
in a future version.
Setting operating system parameters
To run Adaptive Server IQ with many connections you need to change certain
system parameters.
Solaris Although the Solaris thread limit is not a problem, developers and Sybase field
personnel should be aware that using the Solaris debugger on IQ requires a file
descriptor for each thread in addition to the file descriptors for each dbspace.
You need to adjust the number of file descriptors by means of the C shell limit
command and "set rlim_fd_max=4096" in /etc/system.
Tru64-UNIX / Digital
UNIX Adaptive Server IQ needs three threads to support each connection plus some
overhead threads the operating system needs to have its maximum number of
threads adjusted upwards. To accomplish this, you must raise the Digital UNIX
default number of threads, using the formula 60*NUMCPUS +10 +3*. You can
change this value either by editing Digital UNIX’s /etc/sysconfigtab directly or
updating it using a Compaq GUI (see Adaptive Server IQ Installation and
Configuration Guide or your Compaq documentation).