IBM Z10 BC manual z10 Coupling Link Options, Time synchronization and time accuracy on z10 BC

z10 Coupling Link Options

Type	Description	Use	Link	Distance	z10 BC	z10
			data rate		z10 EC	Max
					Max
PSIFB	1x IB-DDR LR	z10 to z10	5 Gbps	10 km unrepeated	12*/32*
				(6.2 miles)
				100 km repeated
PSIFB	12x IB-DDR	z10 to z10	6 GBps	150 meters	12*/32*
		z10 to z9	3 GBps**	(492 ft)***
IC	Internal	Internal	Internal	N/A	32/32	64
	Coupling	Communi-	Speeds			CHPIDS
	Channel	cation
ICB-4	Copper	z10, z9	2 GBps	10 meters***	12/16
	connection	z990, z890		(33 ft)
	between OS
	and CF
ISC-3	Fiber	z10, z9	2 Gbps	10 km	48/48
	connection	z990, z890		unrepeated
	between OS			(6.2 miles)
	and CF			100 km repeated

•The maximum number of Coupling Links combined cannot exceed 64 per server (PSIFB, ICB-4, ISC-3). There is a maximum of 64 Coupling CHPIDs (CIB, ICP, CBP, CFP) per server.

•For each MBA fanout installed for ICB-4s, the number of possible cus- tomer HCA fanouts is reduced by one

*Each link supports definition of multiple CIB CHPIDs, up to 16 per fanout

**z10 negotiates to 3 GBps (12x IB-SDR) when connected to a System z9

***3 meters (10 feet) reserved for internal routing and strain relief

Note: The Infi niBand link data rates of 6 GBps, 3 GBps, 2.5 Gbps, or 5 Gbps do not represent the performance of the link. The actual performance is dependent upon many factors including latency through the adapters, cable lengths, and the type of workload. With Infi niBand coupling links, while the link data rate may be higher than that of ICB (12x IB-SDR or 12x IB-DDR) or ISC-3 (1x IB-SDR or 1x IB-DDR), the service times of coupling operations are greater, and the actual throughput may be less than with ICB links or ISC-3 links.

Time synchronization and time accuracy on z10 BC

If you require time synchronization across multiple servers (for example you have a Parallel Sysplex environment) or you require time accuracy either for one or more System z servers or you require the same time across heterogeneous platforms (System z, UNIX, AIX®, etc.) you can meet these requirements by either installing a Sysplex Timer Model 2 (9037-002) or by implementing Server Time Protocol (STP).

The Sysplex Timer Model 2 is the centralized time source that sets the Time-Of-Day (TOD) clocks in all attached servers to maintain synchronization. The Sysplex Timer Model 2 provides the stepping signal that helps ensure that all TOD clocks in a multi-server environment incre- ment in unison to permit full read or write data sharing with integrity. The Sysplex Timer Model 2 is a key component of an IBM Parallel Sysplex environment and a Geographically Dispersed Parallel Sysplex™ (GDPS®) availability solution for On Demand Business.

The z10 BC server requires the External Time Reference (ETR) feature to attach to a Sysplex Timer. The ETR fea- ture is standard on the z10 BC and supports attachment at an unrepeated distance of up to three kilometers (1.86 miles) and a link data rate of 8 Megabits per second.

The distance from the Sysplex Timer to the server can be extended to 100 km using qualifi ed Dense Wavelength Division Multiplexers (DWDMs). However, the maximum repeated distance between Sysplex Timers is limited to 40 km.

Server Time Protocol (STP)

STP messages: STP is a message-based protocol in which timekeeping information is transmitted between servers over externally defi ned coupling links. ICB-4, ISC- 3, and Infi niBand coupling links can be used to transport STP messages.

Server Time Protocol enhancements

STP configuration and time information restoration

after Power on Resets (POR) or power outage: This

enhancement delivers system management improvements by restoring the STP confi guration and time information after Power on Resets (PORs) or power failure that affects both servers of a two server STP-only Coordinated Timing Network (CTN). To enable this function the customer has to select an option that will assure than no other servers can

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