Hitachi 9900 Series - Manual (Page 13)

Comparison to the Shared Bus Architecture of the Hitachi Freedom
Storage
™ 7700E
Unlike the shared common bus architecture of previous generation storage products,
such as the 7700E (as shown in Figure 3 for reference to a shared bus architecture),
Hi-Star
™ is designed to truly scale in both capacity and performance. This is possible only
with the Lightning 9900 ™ Series’ internally switched architecture which, unlike shared bus
architectures, does not have to contend for limited bus bandwidth.
The Lightning 9900 ™ has an advanced availability profile compared to
competitive products
The Lightning 9900 ™ was designed with maximum emphasis on high availability
computing for today’s most critical enterprises. Figure 15 highlights some of the many
advantages in high-availability design that the Lightning 9900
™ has over competitive
products.
• Active dual-ported disk drives instead of single-port active drives.
• Separate storage for control & configuration tables.
• Mirrored cache instead of single image cache.
1
• Hitachi Data Systems is the leading supplier of storage systems for GDPS
production sites.
• NanoCopy ™ is a superior scheme for disaster recovery.
• High-availability, custom designed disk drives.
Bus contention is
virtually eliminated with
the Hi-Star
™
Architecture.
Figure 3 – System block
diagram of the 7700E’s
shared bus architecture.
Hitachi is the only major
supplier of enterprise
class storage systems with
a 100% availability
guarantee.
Hitachi Data Systems
4
1 Some competitive products do not have dual cache like the Hitachi Lightning 9900 ™ . If there
is an unrecoverable error in cache, there is no duplicate backup copy. With these products
there is an increased risk of lost data, especially if the loss occurs in the hardware status
area. The Lightning 9900
™ does not have this problem since all status areas and write data
are duplexed. Although a minor concern to some given the low probability of occurrence, the
thought of data loss is never comforting to enterprise executives charged with 7x24
operations.