Dell PowerVault 221S (SCSI) - Manual (Page 24)

A REFERENCE GUIDE FOR OPTIMIZING DELL™ SCSI SOLUTIONS VER A02
PAGE 24 11/17/2005
modules is not supported. For more details, refer to section 5 (SCSI Host Bus Adapters /
SCSI RAID).
Actual transfer rate of the SCSI bus is determined by host channel, EMMs and HDDs
installed in PV22xS.
Mixing HDD Capacities
Mixing of different drive sizes is supported, but not recommended. PV22xS currently
supports 18GB, 36GB, 73GB, 146GB, and 300GB capacities, with future support for
higher capacities as they become available. If operating in a RAID configuration, the
lowest capacity drive may define the RAID virtual disk size. For example, with two
different HDDs, one 36GB and one 146GB drive, a RAID1 size will be limited to 36GB.
On a RAID0 array size will be limited to 72GB. The excess space that is not included in
the RAID array may still be partitioned and used. For more details on RAID array
configurations, refer to section 5 (SCSI Host Bus Adapters / SCSI RAID).
Mixing HDD Spindle Speeds
Mixing of different drive spindle speeds is supported; however, it is not recommended.
PV22xS currently supports 10K and 15K rpm spindle speeds, with future support for
higher spindle rates as they become available. If operating in a RAID configuration, the
lowest spindle speed may dictate the maximum performance of the RAID group. For
example, in a RAID5 configuration with 5 drives having 4 HDDs running at 15K RPM and
one running at 10K RPM, effective data transfer rate may be limited to the performance
provided by the 10K RPM drive since all HDDs in the array perform as a single entity.
SCSI Enclosure Services (SES)
Environmental parameters such as temperature and voltage are continuously monitored
by the EMM module. The PV22xS works in conjunction with Dell OpenManage™ to
monitor and manage these parameters. Trigger thresholds can be set to warn the user
when these parameters exceed safe operating levels, and to take specific action to power
down the enclosure when they exceed a critical threshold level for maximum safety and
avoid potential damages before they occur. Both local visual indicators and audio alerts
are provided by the enclosure. By default, the audio alerts on the enclosure are disabled
from the factory and must be enabled by the customer using Dell OpenManage, if desired.
In summary, the following SES functions are provided by the PV22xS enclosure:
• Report enclosure shelf faults
• HDD Power/Fault/Offline status
• Power supply status and shutdown capabilities
• Fan speed status and control
• Temperature monitoring
• Over/Under temperature shutdown capabilities
• Alarms (local audible and visual LED indicators)
Warm and Hot Pluggable Features
The PV22xS enclosure is designed for warm and hot plugging to help prevent damage
when pulling or replacing certain components. Warm and hot plugging are very similar
concepts allowing for the safe removal and replacement of components while the power is
still on. The main difference is that warm plugging requires any I/O operations to be