IBM Z10 EC manual Ficon Support for Cascaded Directors, FCP Channels

FICON Support for Cascaded Directors

Native FICON (FC) channels support cascaded directors. This support is for a single hop confi guration only. Two- director cascading requires a single vendor high integrity fabric. Directors must be from the same vendor since cas- caded architecture implementations can be unique. This type of cascaded support is important for disaster recov- ery and business continuity solutions because it can help provide high availability, extended distance connectivity, and (particularly with the implementation of 2 Gb/sec Inter Switch Links) has the potential for fi ber infrastructure cost savings by reducing the number of channels for intercon- necting the two sites.

FICON cascaded directors have the added value of high integrity connectivity. Integrity features introduced within the FICON Express channel and the FICON cascaded switch fabric to aid in the detection and reporting of any miscabling actions occurring within the fabric can prevent data from being delivered to the wrong end point.

FCP Channels

z10 EC supports FCP channels, switches and FCP/ SCSI disks with full fabric connectivity under Linux on System z and z/VM 5.2 (or later) for Linux as a guest under z/VM, under z/VM 5.2 (or later), and under z/VSE 3.1 for system

usage including install and IPL. Support for FCP devices means that z10 EC servers are capable of attaching to select FCP-attached SCSI devices and may access these devices from Linux on z10 EC and z/VSE. This expanded attachability means that enterprises have more choices for new storage solutions, or may have the ability to use existing storage devices, thus leveraging existing invest- ments and lowering total cost of ownership for their Linux implementations.

The same FICON features used for native FICON chan- nels can be defi ned to be used for Fibre Channel Protocol (FCP) channels. FCP channels are defi ned as CHPID type FCP. The 4 Gb/sec capability on the FICON Express4 channel means that 4 Gb/sec link data rates are available for FCP channels as well.

FCP – increased performance for small block sizes

The Fibre Channel Protocol (FCP) Licensed Internal Code has been modifi ed to help provide increased I/O operations per second for small block sizes. With FICON Express4, there may be up to 57,000 I/O operations per second (all reads, all writes, or a mix of reads and writes), an 80% increase compared to System z9. These results are achieved in a laboratory environment using one channel confi gured as CHPID type FCP with no other processing occurring and do not represent actual fi eld measurements. A signifi cant increase in I/O operations per second for small block sizes can also be expected with FICON Express2.

This FCP performance improvement is transparent to operating systems that support FCP, and applies to all the FICON Express4 and FICON Express2 features when confi gured as CHPID type FCP, communicating with SCSI devices.

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