Specifications

Escala Tower PL & S, E, T System Hardware
Chapter 3: External Storage and SAN Subsystems 69/116
9es3s1c3.doc
Rev 5.9
02/12/2003
5.3.8. SRDF Remote Link Director
The Remote Link Director (RLD) is a 4-port serial channel director microcode configured as the link
between Symmetrix units in a Symmetrix Remote Data Facility (SRDF) configuration. The Remote
Link Director (RLD) interfaces to Symmetrix channels via a serial channel interface adapter. The
Remote Link Director supports up to 1,024 logical volumes per board. Symmetrix requires a minimum
of two RLDs in each Symmetrix unit used in an SRDF configuration. When one of the processors of a
serial channel director (two ports on each processor) is configured as an RLD,
only one of the ports
on
that processor can be configured as a remote link, while the remaining port is not used. If two ports of
the four-port RLD are needed as remote links to other Symmetrix units, only one port from each
processor can be used.
For open systems, SRDF over Fibre Channel implementations use Remote Fibre Directors (RFD) for
connecting Symmetrix systems using high-speed Fibre Channel links. These directors are multi-mode
fiber and only one of the two ports is usable for the remote connection. The minimum microcode
version required for this director is 5x66.
5.3.9. Cache Memory
One of the most crucial components of a Symmetrix system is the cache memory. All read or write
operations transfer data to or from cache. Any transfers between the host processor, Channel Directors,
and cache are achieved at electronic speeds that are a quantum leap faster than transfers involving disk.
Optimization around the movement of data between disk and cache results in the highest performance
possible. There are two cache buses, x and y; each has a 360MB per second bandwidth for a total
processing bandwidth of 720MB per second.
5.3.10. Disk Drives
Symmetrix systems use advanced technology disk drives and disk controllers to enhance Symmetrix
capabilities. Microprocessors embedded in the controllers of each drive enable capabilities such as
advanced RAID protection to be offloaded from CPUs, disk directors and controllers. This further
enhances the performance of Symmetrix systems and also serves to make them more easily compatible
with a wide array of hardware and software platforms.
Symmetrix 3630, 3830, and 3930systems support mixed configurations of up to 32, 96, and 256
(respectively) 18GB and 36GB disks drives. This breadth of scalable capacity and configuration
choices allows Symmetrix systems to adapt to virtually any enterprise storage requirement.