Intel
®
RAID Software User’s Guide 25
Servers that support video-on-demand typically read the data often, but write data
infrequently. Both the read and write operations tend to be long. Data stored on a general-
purpose file server involves relatively short read and write operations with relatively small
files.
Dimmer Switch Feature
Powering and cooling drives represents a major cost for data centers. The new MegaRAID
Dimmer™ Switch reduces the power consumption of the devices connected to a MegaRAID
controller. This helps to share resources more efficiently and lower costs.
With Dimmer Switch, any unconfigured drive connected to a MegaRAID controller is spun
down after 30 minutes of inactivity, reducing its power usage. Spun down drives are spun up
automatically when you create a configuration using those drives.
Number of Physical Disks
Your configuration planning for the SAS RAID controller depends in part on the number of
physical disks that you want to use in a RAID array. The number of drives in an array
determines the RAID levels that can be supported. Only one RAID level can be assigned to
each virtual disk.
MegaRAID Fast Path
The MegaRAID Fast Path Premium Feature is a high performance IO Accelerator technology
for Solid State Drive RAID Arrays connected to a MegaRAID adapter. There are two “Levels”
to this feature. Level 1 Fast Path enabled by default without PFK. The “Standard” or Level 1
Fast Path pertains to general IO Path improvements to Write Through data transfers.
Additionally, controller cache tuning has resulted in improvements to configurations
leveraging write back mode.
Level 2 Fast Path enabled automatically with Intel
®
RAID Premium Feature Key
AXXRPFKSSD or AXXRPFKSSD2 installed. Level 2 Fast Path is SSD-centric. This is where
the Premium Feature kicks in by supporting full optimization of SSD Virtual Disk groups.
With this premium feature enabled, Solid State Drive configurations tuned for small, random
block-size IO activity -- typical of transactional database applications -- can sustain higher
numbers of IO READs Per Second, compared with Level 1 Fast Path. The performance levels
reached with this solution are equivalent to those of much costlier Flash-based adapter card
solutions.
Refer to Intel
®
RAID Premium Feature Key AXXRPFKSSD, AXXRPFKDE, and
AXXRPFKSNSH Installation Guide (E88588-00x) or Intel
®
RAID Premium Feature Keys
AXXRPFKSSD2, AXXRPFKDE2, and AXXRPFKSNSH2 Installation Guide (G29824-00x) for
description of the Premium Feature Key (PFK).
4K Sector Drive Support
The disk drive industry is in transition to support disk drives with native formatting of 4K
sectors. 4K formatted drives provide an opportunity to improve capacity and error correction
efficiencies as capacities grow, and as improvements in error correction are implemented.
Drives supporting 4K sectors will also support a 512 byte emulation mode which will allow
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