IBM s/390 manual Disk caches, System A, System B, System C

A conceptual network is shown in Figure 5-1.In this example, a single instance of FLEX-ES is executing (in system B in the center of the figure). It is using remote resources on the other two systems; disk resources on system A and a tape drive on system C. The FLEX-ES resource managers in all three systems communicate with each other. The emulated S/390 is unaware that some of the emulated devices are on remote systems.

System and device definitions are required on all three systems. These would include the following lines:

System A:

adisk: cu 3990 interface network(1)

System B:

channel(3) network channel(4) network

cu devad... path(3) resource(adisk) cu devad... path(4) resource(atape)

System C:

atape: cu 3480 interface network(1)

		OS/390	B
		FLEX-ES			C
A
				resource
			resource		tape
		ckd		manager
			manager		emulation
resource	ckd	emulation
manager	emulation
Linux		Linux		UnixWare
	LAN		LAN	LAN
S/390 volumes		S/390 volumes

Figure 5-1 FLEX-ES Networking

5.10 Disk caches

FLEX-ES automatically caches 15 tracks of data for each emulated 3390 or 3380. You can adjust this in three ways:

￿Specify a different number of tracks to cache for a particular emulated drive.

￿Specify a different number of tracks to cache at the control unit level; excess tracks (above those needed for the specified or default cache for each device on the control unit) will float, as needed, among all the devices on the control unit.

50S/390 PID: ThinkPad Enabled for S/390