6 DS8000 Series: Concepts and Architecture
1.2.1 Hardware overview
The hardware has been optimized to provide enhancements in terms of performance,
connectivity, and reliability. From an architectural point of view the DS8000 series has not
changed much with respect to the fundamental architecture of the previous ESS models and
75% of the operating environment remains the same as for the ESS Model 800. This ensures
that the DS8000 can leverage a very stable and well-proven operating environment, offering
the optimum in availability.
The DS8000 series features several models in a new, higher-density footprint than the ESS
Model 800, providing configuration flexibility. For more information on the different models
see Chapter 6, “IBM TotalStorage DS8000 model overview and scalability” on page 103.
In this section we give a short description of the main hardware components.
POWER5 processor technology
The DS8000 series exploits the IBM POWER5 technology, which is the foundation of the
storage system LPARs. The DS8100 Model 921 utilizes the 64-bit microprocessors’ dual
2-way processor complexes and the DS8300 Model 922/9A2 uses the 64-bit dual 4-way
processor complexes. Within the POWER5 servers the DS8000 series offers up to 256 GB of
cache, which is up to 4 times as much as the previous ESS models.
Internal fabric
DS8000 comes with a high bandwidth, fault tolerant internal interconnection, which is also
used in the IBM pSeries Server. It is called RIO-2 (Remote I/O) and can operate at speeds up
to 1 GHz and offers a 2 GB per second sustained bandwidth per link.
Switched Fibre Channel Arbitrated Loop (FC-AL)
The disk interconnection has changed in comparison to the previous ESS. Instead of the SSA
loops there is now a switched FC-AL implementation. This offers a point-to-point connection
to each drive and adapter, so that there are 4 paths available from the controllers to each disk
drive.
Fibre Channel disk drives
The DS8000 offers a selection of industry standard Fibre Channel disk drives. There are
73 GB with 15k revolutions per minute (RPM), 146 GB (10k RPM) and 300 GB (10k RPM)
disk drive modules (DDMs) available. The 300 GB DDMs allow a single system to scale up to
192 TB of capacity.
Host adapters
The DS8000 offers enhanced connectivity with the availability of four-port Fibre
Channel/FICON® host adapters. The 2 Gb/sec Fibre Channel/FICON host adapters, which
are offered in longwave and shortwave, can also auto-negotiate to 1 Gb/sec link speeds. This
flexibility enables immediate exploitation of the benefits offered by the higher performance,
2 Gb/sec SAN-based solutions, while also maintaining compatibility with existing 1 Gb/sec
infrastructures. In addition, the four-ports on the adapter can be configured with an intermix of
Fibre Channel Protocol (FCP) and FICON. This can help protect your investment in fibre
adapters, and increase your ability to migrate to new servers. The DS8000 also offers
two-port ESCON® adapters. A DS8000 can support up to a maximum of 32 host adapters,
which provide up to 128 Fibre Channel/FICON ports.
