Filter
Top Products
38 DS8000 Series: Concepts and Architecture
The ESCON adapter in the DS8000 is a dual ported host adapter for connection to older
zSeries hosts that do not support FICON. The ports on the ESCON card use the MT-RJ type
connector.
Control units and logical paths
ESCON architecture recognizes only 16 3990 logical control units (LCUs) even though the
DS8000 is capable of emulating far more (these extra control units can be used by FICON).
Half of the LCUs (even numbered) are in server 0, and the other half (odd-numbered) are in
server 1. Because the ESCON host adapters can connect to both servers, each adapter can
address all 16 LCUs.
An ESCON link consists of two fibers, one for each direction, connected at each end by an
ESCON connector to an ESCON port. Each ESCON adapter card supports two ESCON
ports or links, and each link supports 64 logical paths.
ESCON distances
For connections without repeaters, the ESCON distances are 2 km with 50 micron multimode
fiber, and 3 km with 62.5 micron multimode fiber. The DS8000 supports all models of the IBM
9032 ESCON directors that can be used to extend the cabling distances.
Remote Mirror and Copy with ESCON
The initial implementation of the ESS 2105 Remote Mirror and Copy function (better known
as PPRC or Peer-to-Peer Remote Copy) used ESCON adapters. This was known as PPRC
Version 1. The ESCON adapters in the DS8000 do not support any form of Remote Mirror
and Copy. If you wish to create a remote mirror between a DS8000 and an ESS 800 or
another DS8000 or DS6000, you must use Fibre Channel adapters. You cannot have a
remote mirror relationship between a DS8000 and an ESS E20 or F20 because the E20/F20
only support Remote Mirror and Copy over ESCON.
ESCON supported servers
ESCON is used for attaching the DS8000 to the IBM S/390 and zSeries servers. The most
current list of supported servers is at this Web site:
http://www.storage.ibm.com/hardsoft/products/DS8000/supserver.htm
This site should be consulted regularly because it has the most up-to-date information on
server attachment support.
2.5.1 FICON and Fibre Channel protocol host adapters
Fibre Channel is a technology standard that allows data to be transferred from one node to
another at high speeds and great distances (up to 10 km and beyond). The DS8000 uses
Fibre Channel protocol to transmit SCSI traffic inside Fibre Channel frames. It also uses Fibre
Channel to transmit FICON traffic, which uses Fibre Channel frames to carry zSeries I/O.
Each DS8000 Fibre Channel card offers four 2 Gbps Fibre Channel ports. The cable
connector required to attach to this card is an LC type. Each port independently
auto-negotiates to either 2 Gbps or 1 Gbps link speed. Each of the 4 ports on one DS8000
adapter can also independently be either Fibre Channel protocol (FCP) or FICON, though the
ports are initially defined as switched point to point FCP. Selected ports will be configured to
FICON automatically based on the definition of a FICON host. Each port can be either FICON
or Fibre Channel protocol (FCP). The personality of the port is changeable via the DS
Storage Manager GUI. A port cannot be both FICON and FCP simultaneously, but it can be
changed as required.