Intel RAID Controllers - Best Practices white paper

Intel® RAID Controllers Best Practices White Paper
Revision 1.0
6
A backup plan should be an integral part of a healthy data security system. Computers and
computer components can and do fail. Multiple disk failures in RAID configurations, data center
catastrophes (no matter how small) and virus infections can take down a system and corrupt
critical data. Often there is no warning before a failure, and then it is too late.
Data loss can be costly and may impact productivity both in terms of lost opportunity when there
is no access to data, and in terms of effort and expense to recover missing data. In some
situations, data may not be recoverable.
Implementing a backup plan will often turn several days of lost productivity and weeks of
reorganizing information into an hour of restoring a disk image. A good backup strategy will
include maintaining multiple copies of data that have been made over time so that you can
recover the latest backup or step back to data files that were copied days or weeks earlier as
needed. Depending on the criticality of your data and to guard against a catastrophic event, it
may be a good idea to store a regular backup securely off site.
Backup copies of data can be made to a local drive or tape drive, or to a remote data backup
service provider.
It is especially important to keep a copy of data that is held on storage systems or RAID arrays.
Due to the large capacity of some drives and the time required to rebuild data, there is an
increased risk that additional drives may fail during the rebuild, resulting in possible data loss.
Even though there is redundancy built into a RAID or Storage system, a backup should be
performed on a regular basis.
4. Tuning Controller Performance
Optimizing the overall performance of a RAID subsystem requires careful consideration of
several factors that can affect performance, including the controller and disk drive cache
settings and the interaction of these settings with system applications. The sections below
provide a limited discussion of some of these factors. For a full review of performance tuning
please refer to the Intel
®
RAID Controller Performance Optimization whitepaper, available at
http://support.intel.com/support/motherboards/server/
.
Note: There are a variety of factors that can affect the performance of the RAID subsystem
including PCI bus bandwidth, logical drive cache settings, stripe size, hard disk drive cache
settings, RAID level, ratio of read versus write operations, ratio of sequential versus random
operations, and the number of disks in an array.
4.1 Tuning Controller Cache Options
Tuning cache memory options on the RAID controller can improve performance. There are
three settings available in the controller cache to allow fine tuning:
 Read Ahead Option
 Write Back Option
 Cached I/O Option