User`s guide

A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00
PAGE 12 5/06/2005
Mixing Physical Disk Capacities
By supporting the mixing of physical disk of different sizes within an enclosure, the PowerVault
MD1000 storage enclosure enables optimal matching of physical disk type to the requirements of
multiple applications. Mixing of physical disk sizes is supported but not recommended within a
single RAID group. The PowerVault MD1000 storage enclosure supports 36 GB, 73 GB, 146 GB,
and 300 GB capacities for SAS. When operating in a RAID configuration, the lowest capacity
physical disk defines the RAID virtual disk size. For example, a RAID 1 configuration with two
different sized physical disks, one 36 GB and another 146 GB physical disk, will be limited to 36
GB. If the same two physical disks were configured in RAID 0 configuration, the virtual disk size
would be limited to 73 GB (the equivalent of two 36 GB physical disks in RAID 0 configuration).
Mixing Physical Disk Spindle Speeds
Mixing different physical disk spindle speeds is supported, but not recommended within a single
RAID group. The PowerVault MD1000 storage enclosure supports 10,000 and 15,000 RPM
spindle speeds. Depending upon the RAID configuration, the lowest spindle speed may dictate the
maximum performance of the RAID group.
SCSI Enclosure Services (SES)
The EMM continuously monitors environmental variables such as temperature and voltage. The
PowerVault MD1000 storage enclosure works in conjunction with Dell OpenManage Server
Administrator to set trigger thresholds that warn the user when these variables exceed safe
operating levels. The enclosure will automatically power down when these environmental variables
exceed a critical threshold level in order to avoid potential equipment damage. Both local visual
indicators (e.g. LEDs) and audio alerts are triggered when faults are detected. The audio alerts on
the enclosure are disabled by default, but can be enabled using Server Administrator. The
following SES functions are provided by the EMMs in the PowerVault MD1000 storage enclosure:
• Enclosure shelf faults detection
• Physical disk 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)
Hot Plugging
• The PowerVault MD1000 storage enclosure is designed for hot plugging certain
components to help prevent damage when pulling or replacing. Hot plugging is a concept
which allows for the safe removal and replacement of components while the power is still
on. Hot plugging allows server applications and disk activities to continue uninterrupted,
while maintenance or repair actions take place. Additional steps may be required for
physical disks to become usable. See the RAID controller User’s Guide for more
information.
• Hot Pluggable Devices
o Physical disk (all Disk I/O activities must be halted first)
o Power supply module/ cooling fan module
Note: Hot plugging of SAS cables is not supported.