In order of likely best performance when using DB2 Connect, various types of network attachment include:
The last option is not recommended - see below.
The recommended best way to connect to the host is to use ESCON channel attachment cards for AIX or Windows NT. The IBM 3172 Model 3 and 2216 also perform well, but they tend to deliver throughput inferior to ESCON.
When using AIX with ESCON cards, please apply the PTFs related to MPC (Multi Path Channel). Without these PTFs the AIX SNA ESCON driver may deliver worse performance. See Multi Path Channel Support for SNA over ESCON for more details. Further information can also be found at:
http://www.networking.ibm.com.cms/cmsnew01.html
See How to Tune DB2 Connect Connections via NCP for a checklist of which Communications Server, NCP, and VTAM parameters to tune to optimize DB2 Connect performance. All the non-NCP specific recommendations are applicable to all types of DB2 Connect and client/server attachments.
The OSA-2 card on System 390 might not deliver throughput as high as a 3272 Model 3 when there is a high volume of small transactions, owing to its lower frames-per-second capability. See Information about OSA-2 Enhancements for details of some recent enhancements.
3145 with NCP is usually tuned specifically for existing network traffic. Consequently it might not perform as well for database client/server applications. Most DB2 Connect performance problems are due to the time delay between the NCP and VTAM and/or between NCPs. See How to Tune DB2 Connect Connections via NCP, which provides a tuning checklist.
In general, we recommend avoiding the use of 3174 Terminal Controllers because their packet size (RU size) of 256 bytes is too small. 3174 microcode level C is required in order to provide Independent LU support for APPC database connections. Some OEM 3174 equivalents may have similar dependencies.