IBM Z10 EC - Manual (Page 21)

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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