Reliability, Availability, and Serviceability (RAS)
The ST9985V is not expected to fail in any way that would interrupt user access to data. The ST9985V can
sustain multiple component failures and still continue to provide full access to all stored user data.
Note: While access to user data is never compromised, the failure of a key component can degrade
performance.
The reliability, availability, and serviceability features of the ST9985V include:
Highly Available. The ST9985V provides highly available architecture for all critical components. The
subsystem is protected against disk drive error and failure by enhanced RAID technologies and dynamic
scrubbing and sparing. The ST9985V uses component and function redundancy to provide high availability
for all other subsystem components (microprocessors, control storage, power supplies, etc.). The ST9985V
has no active single point of component failure and is designed to provide continuous access to all user data.
Separate power supply systems. Each storage cluster is powered by a separate set of power supplies. Each
set can provide power for the entire subsystem in the unlikely event of power supply failure. The power
supplies of each set can be connected across power boundaries, so that each set can continue to provide
power if a power outage occurs. The ST9985V can sustain the loss of multiple power supplies and still
continue operation.
New – battery backup and de-stage option for HDDs. A new feature of the ST9985V provides separate
battery backup for the hard disk drives (HDDs) with an optional setting to de-stage data from cache to the
(internal) HDDs during a power outage.
Note: The de-stage option is not supported when external storage is connected and/or when Cache
Residency Manager BIND mode is applied.
Dynamic scrubbing and sparing for disk drives. The ST9985V uses special diagnostic techniques and
dynamic scrubbing to detect and correct disk errors. Dynamic sparing is invoked automatically if needed.
The ST9985V can be configured with up to 40 spare disk drives (4 + 36 optional), and any spare disk can
back up any other disk of the same speed (RPMs) and the same or less capacity, even if the failed disk and
spare disk are in different array domains (attached to different back-end directors).
Dynamic duplex cache. The ST9985V cache is divided into two equal segments on separate power
boundaries. The ST9985V places all write data in both cache segments with one internal write operation, so
the data is always duplicated (duplexed) across power boundaries. If one copy of write data is defective or
lost, the other copy is immediately de-staged to disk. This duplex design ensures full data integrity in the
event of a cache or power failure.
Remote copy features. The ST9900 Universal Replicator, ST9900 TrueCopy, and Compatible Replication
for IBM XRC data movement features enable users to set up and maintain duplicate copies of mainframe
and open-system data over extended distances. In the event of a system failure or site disaster, the secondary
copy of data can be invoked rapidly, allowing applications to be recovered with guaranteed data integrity.
Hi-Track. The Hi-Track maintenance support tool monitors the operation of the ST9985V at all times,
collects hardware status and error data, and transmits this data to the ST9900 Data Systems Support Center.
The Support Center analyzes the data and implements corrective action as needed. In the unlikely event of a
component failure, Hi-Track contacts the ST9900 Data Systems Support Center immediately to report the
failure without requiring any action on the part of the user. Hi-Track enables most problems to be identified
and fixed prior to actual failure, and the advanced redundancy features enable the subsystem to remain
operational even if one or more components fail.
Note: Hi-Track does not have access to any user data stored on the ST9985V.
Non-disruptive service and upgrades. All hardware upgrades can be performed non-disruptively during
normal system operation. All hardware sub-assemblies can be removed, serviced, repaired, and/or replaced
non-disruptively during normal system operation. Shared memory for the ST9985V is installed on separate
PCBs, and the fibre-channel PCBs for the ST9985V are equipped with hot-swappable fibre SFP transceivers
Just the Facts
October 2007
64
Sun Confidential – For Internal Use and Authorized Partner Use Only
