## Request servers 

A listening request server receives a connection request from a client, establishes a connection, and then accepts requests from that client. The following request servers are available: 

GLYPH<SM590000> VSMREQIN 

GLYPH<SM590000> VSMREQI6 

GLYPH<SM590000> VSMREQIU 

GLYPH<SM590000> VSMEVSRV 

## Worker servers 

The worker servers process API function requests. The following worker servers are defined in the default installation: 

GLYPH<SM590000> VSMWORK1 

GLYPH<SM590000> VSMWORK2 

GLYPH<SM590000> VSMWORK3 

A fourth worker server, VSMGUARD, is also defined. VSMGUARD is a “guard” server that helps provide better resiliency and error recovery. For more information, see 6.3.3, “VSMGUARD” on page 169. 

## Other servers 

The following severs also are available: 

GLYPH<SM590000> The LOHCOST server is used for caching the system directory contents that are required to satisfy the various query APIs. It is also used to store and retrieve data that is used by the metadata APIs. 

GLYPH<SM590000> The DTCSMAPI server is used by several of the SMAPI servers for communication and workload balancing. 

GLYPH<SM590000> The PERSMAPI server is used for performance monitoring. 

GLYPH<SM590000> The VSMEVSRV server is used to listen for and then propagate VMEVENT and directory updates. 

GLYPH<SM590000> The OPERATNS server is used to collect, format, and distribute ABEND memory dumps. 

## 6.3.3 VSMGUARD 

The VSMGUARD worker server grants authority to all the other SMAPI servers that are configured to access the SMAPI file space. Therefore, VSMGUARD must be made an administrator of the VMSYS: file pool. This process is done by adding VSMGUARD to the list of users that are authorized for ADMIN authority. 

Note:  In the default environment, this process is done by updating the VMSERVS DMSPARMS file on the VMSERVS 191 disk. 

VSMGUARD has an important role in the SMAPI environment. When you must recycle all SMAPI user IDs, you do it by recycling VSMGUARD ( force  and xautolog ) and it recycles all the other SMAPI user IDs, saves the SMAPI segment, and defines the vSwitches that are listed in the configuration file. 

Note:  For more information about SMAPI, see The Systems Management Application Programming for 6.4 , SC24-6327. 

