Mainframe HiperSockets is a technology that provides high-speed
TCP/IP connectivity within a central processor complex. It eliminates
the need for any physical cabling or external networking connection
between servers running in different LPARs.
The communication is through the system memory of the processor,
so servers are connected to form a "internal LAN."
The HiperSockets implementation is based on the OSA-Express Queued
Direct I/O (QDIO) protocol, hence HiperSockets is also called internal
QDIO, or IQDIO. The microcode emulates the link control layer of an
OSA-Express QDIO interface.
Figure 1 shows
how to use HiperSockets; of particular note is that z/OS is not the
only operating system running on a mainframe host that can take advantage
of HiperSockets. Other operating systems include z/VM and Linux.
Note: z/VM is capable of functioning very similar
to an LPAR. Instead of doing the work at the hardware level, z/VM
creates separate virtual environments using software. It is highly
efficient and it is sometimes used to run large numbers of separate
and independent Linux hosts, all within a single LPAR.
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Figure 1. HiperSockets usage example
- HiperSockets with CHPID FC
This HiperSockets channel path exclusively
serves three Linux systems running in LPAR-2, LPAR-3, and LPAR- 4.
- HiperSockets with CHPID FD
Connected to this HiperSockets channel
path are all servers in the mainframe CPC, which are:
- The multiple Linux servers running under z/VM in LPAR-1
- The z/VM TCP/IP stack running in LPAR-1
- The three Linux servers in LPARs 2 to 4
- All z/OS servers in sysplex A (LPARs 5 to 7) for non-sysplex traffic
- All z/OS servers in sysplex B (LPARs 8 to 10) for non-sysplex
traffic
- HiperSockets with CHPID FE
This is the connection used by sysplex
A (LPARs 5 to 7) to transport TCP/IP user-data traffic among the three
sysplex LPARs.
- HiperSockets with CHPID FF
This is the connection used by sysplex
B (LPARs 8 to 10) to transport TCP/IP user-data traffic among the
three sysplex LPARs.
The CHPID type used for a HiperSockets connection is called IQD.
Note: So how fast
is IQDIO? How about transferring data between z/OS and Linux using
FTP? First, multiple FTP connections must be run in order to get close
to utilizing the bandwidth of the interface. When transferring data
between a z/OS LPAR and a Linux LPAR over IQDIO, 50 FTP connections
produced a total throughput of 600 MBps. The limitation here, however
is not z/OS. In order to increase the throughput, the Linux limitation
needs to be overcome. The test was expanded to FTP connections between
a single z/OS LPAR and 4 separate Linux LPARs. With 120 total FTP
connections (30 for each Linux LPAR), the IQDIO throughput was over
1200 MBps, or more than 1.2 GBps.
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