Dell PowerVault MD1120 Optimization Manual page 15

A REFERENCE GUIDE FOR OPTIMIZING DELL™ POWERVAULT™ MD1XXX FAMILY SAS SOLUTION
Note: Hot plugging of SAS cables is not supported.
External SAS Cables
Depending on the enclosure topology, one or two external SAS cables may be attached between
the host system(s) and a PowerVault MD1xxx Family storage enclosure. SAS cables use four
active 3 Gbps SAS lanes in a single cable to deliver an aggregate of 12.0 Gbps connection. All
PowerVault MD1xxx Family SAS cables purchased from Dell have been tested and comply with
the ANSI SAS 1.0 standard. Dell supports using only Dell-provided cables.
External SAS Connector Types
SAS uses a 25-pin connector whose specification is governed by the SFF-8470 specification. For
more information, refer to the specification referenced in Appendix A.
Regardless of the physical topology, PowerVault MD1xxx Family storage enclosures also provide
some common capabilities as listed below:
Redundancy Capabilities
•
Management Redundancy
With two EMMs installed, a PowerVault MD1xxx Family storage enclosure's internal
enclosure functions such as temperature regulation, LED control, and alarm control, are
maintained in the event of an EMM failure. However, even with dual EMMs installed,
enclosure status will not be reported to the host in the event of an EMM failure.
•
Power Supply and Cooling Redundancy
PowerVault MD1xxx Family storage enclosures require that both power supplies be
installed for normal operation. A system can operate using a single power supply for a
limited time in the event a power supply fails or is removed for service.
PowerVault MD1xxx Family storage enclosures provide individually controlled fans. The
units is thermally designed to continue operating in the event of one fan blower failure (n+1
cooling redundancy). In the event of a fan failure, the power supply containing the failed
fan must be replaced.
Reliability Capabilities
•
Thermal Reliability
A fully-redundant PowerVault MD1xxx Family storage enclosure contains four digital
temperature sensors, two on the backplane and one on each EMM. In conjunction with
the SES processor, the temperature sensors provide device protection against adverse
thermal conditions. PowerVault MD1xxx Family storage enclosures are designed to
operate within ambient temperature range of 10°C (50°F) to 35°C (95°F). When either of
the backplane sensors detects temperature below 3°C (37.4°F) or above 55°C (131°F),
the SES processor notifies the host of a critical temperature situation. This triggers the
host to perform a graceful shutdown of the enclosure within three minutes. In the event
that the host is unable to initiate the enclosure shutdown process or a host is not
connected to the enclosure, a PowerVault MD1xxx Family storage enclosure has an
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6/16/2008