Avago Technologies MegaRAID Fast Path Software - Manual (Page 16)

Page 16 LSI Corporation Confidential | July 2011
MegaRAID SAS Software User Guide Chapter 1: Overview | Dimmer Switch Features
1.4.1 SSD Guard SSD Guard, a feature that is unique to MegaRAID, increases the reliability of SSDs by
automatically copying data from a drive with potential to fail to a designated hot spare
or newly inserted drive. Because SSDs are more reliable than hard disk drives (HDDs),
non-redundant RAID 0 configurations are much more common than in the past. SSD
Guard offers added data protection for RAID 0 configurations.
SSD Guard works by looking for a predictive failure while monitoring the SDD
Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) error log. If errors
indicate that a SSD failure is imminent, the MegaRAID software starts a rebuild to
preserve the data on the SSD and sends appropriate warning event notifications.
1.5 Dimmer Switch Features Powering drives and cooling drives represent a major cost for data centers. The
MegaRAID Dimmer Switch feature set reduces the power consumption of the devices
connected to a MegaRAID controller. This helps to share resources more efficiently and
lowers the cost.
Dimmer Switch I - Spin down unconfigured disks. This feature is configurable and can
be disabled.
Dimmer Switch II - Spin down Hot Spares. This feature is configurable and can be
disabled.
Dimmer Switch III - This new feature spins down any Logical Disk after 30 minutes of
inactivity, by default, if the array can be spun up within 60 seconds. This feature is
configurable and can be disabled.
1.6 UEFI 2.0 Support UEFI 2.0 provides MegaRAID customers with expanded platform support. The
MegaRAID UEFI 2.0 driver, a boot service device driver, handles block IO requests and
SCSI pass-through (SPT) commands, and offers the ability to launch pre-boot
MegaRAID management applications through a driver configuration protocol (DCP).
The UEFI driver also supports driver diagnostic protocol, which allows administrators to
access pre-boot diagnostics.
1.7 Configuration Scenarios You can use the SAS RAID controllers in three scenarios:
 Low-end, Internal SATA II Configurations
In these configurations, use the RAID controller as a high-end SATA II-compatible
controller that connects up to 8 disks either directly or through a port expander.
These configurations are mostly for low-end or entry servers. Enclosure
management is provided through out-of-band Inter-IC (I2C) bus. Side bands of both
types of internal SAS connectors support the SFF-8485 (SGPIO) interface.
 Midrange Internal SAS Configurations
These configurations are like the internal SATA II configurations, but with high-end
disks. These configurations are more suitable for low-range to midrange servers.
 High-end External SAS/SATA II Configurations
These configurations are for both internal connectivity and external connectivity,
using SATA II drives, SAS drives, or both. External enclosure management is
supported through in-band, SCSI-enclosed storage. The configuration must
support STP and SMP.