Filter
Top Products
14 DS8000 Series: Concepts and Architecture
offer the most value to the customers. On the list of possible applications are, for example,
Backup/Recovery applications (TSM, Legato, Veritas, and so on).
1.4 Performance
The IBM TotalStorage DS8000 offers optimally balanced performance, which is up to six
times the throughput of the Enterprise Storage Server Model 800. This is possible because
the DS8000 incorporates many performance enhancements, like the dual-clustered
POWER5 servers, new four-port 2 GB Fibre Channel/FICON host adapters, new Fibre
Channel disk drives, and the high-bandwidth, fault-tolerant internal interconnections.
With all these new components, the DS8000 is positioned at the top of the high performance
category.
1.4.1 Sequential Prefetching in Adaptive Replacement Cache (SARC)
Another performance enhancer is the new self-learning cache algorithm. The DS8000 series
caching technology improves cache efficiency and enhances cache hit ratios. The
patent-pending algorithm used in the DS8000 series and the DS6000 series is called
Sequential Prefetching in Adaptive Replacement Cache (SARC).
SARC provides the following:
Sophisticated, patented algorithms to determine what data should be stored in cache
based upon the recent access and frequency needs of the hosts
Pre-fetching, which anticipates data prior to a host request and loads it into cache
Self-Learning algorithms to adaptively and dynamically learn what data should be stored
in cache based upon the frequency needs of the hosts
1.4.2 IBM TotalStorage Multipath Subsystem Device Driver (SDD)
SDD is a pseudo device driver on the host system designed to support the multipath
configuration environments in IBM products. It provides load balancing and enhanced data
availability capability. By distributing the I/O workload over multiple active paths, SDD
provides dynamic load balancing and eliminates data-flow bottlenecks. SDD also helps
eliminate a potential single point of failure by automatically re-routing I/O operations when a
path failure occurs.
SDD is provided with the DS8000 series at no additional charge. Fibre Channel (SCSI-FCP)
attachment configurations are supported in the AIX, HP-UX, Linux, Microsoft® Windows,
Novell NetWare, and Sun Solaris environments.
1.4.3 Performance for zSeries
The DS8000 series supports the following IBM performance innovations for zSeries
environments:
FICON extends the ability of the DS8000 series system to deliver high bandwidth potential
to the logical volumes needing it, when they need it. Older technologies are limited by the
bandwidth of a single disk drive or a single ESCON channel, but FICON, working together
with other DS8000 series functions, provides a high-speed pipe supporting a multiplexed
operation.
Parallel Access Volumes (PAV) enable a single zSeries server to simultaneously
process multiple I/O operations to the same logical volume, which can help to significantly