Overview - IBM N Series Hardware Manual

18.1 Overview

FCP SAN boot, remote boot, and
system is installed on a logical drive not resident locally to the server chassis. SAN Boot has
the following primary benefits over booting the host OS from local storage:
The ability to create a Snapshot of the host OS
You can create a Snapshot of the OS before installing a hotfix, service pack, or other risky
change to the OS. If it goes bad, you can restore the OS from the copy. For more
information about Snapshot technology, see:
http://www.ibm.com/systems/storage/network/software/snapshot/index.html
Performance
The host is likely to boot significantly faster in a SAN boot configuration because you can
put several spindles under the boot volume.
Fault tolerance
There are multiple disks under the volume in a RAID 4 or RAID-DP configuration.
The ability to clone FlexVols, creating FlexClone volumes
This host OS cloned LUN can be used for testing purposes. Further information about
FlexClone software can be found at:
http://www.ibm.com/systems/storage/network/software/flexvol/index.html
Interchangeable servers
By allowing boot images to be stored on the SAN, servers are no longer physically bound
to their startup configurations. Therefore, if a server fails, you can easily replace it with
another generic server. You can then resume operations with the exact same boot image
from the SAN. Only some minor reconfiguration is required on the storage system. This
quick interchange helps reduce downtime and increases host application availability.
Provisioning for peak usage
Because the boot image is available on the SAN, it is easy to deploy additional servers to
temporarily cope with high workloads.
Centralized administration
SAN boot enables simpler management of the startup configurations of servers. You do
not need to manage boot images at the distributed level at each individual server. Instead,
SAN boot allows you to manage and maintain the images at a central location in the SAN.
This feature enhances storage personnel productivity and helps to streamline
administration.
Uses the high availability features of SAN storage
SANs and SAN-based storage are typically designed with high availability in mind. SANs
can use redundant features in the storage network fabric and RAID controllers to ensure
that users do not incur any downtime. Most boot images on local disks or direct-attached
storage do not share this protection. Using SAN boot allows boot images to take
advantage of the inherent availability built into most SANs. This configuration helps to
increase availability and reliability of the boot image, and reduce downtime.
Efficient disaster recovery process
You can have data (boot image and application data) mirrored over the SAN between a
primary site and a recovery site. With this configuration, servers can take over at the
secondary site if a disaster occurs on servers at the primary site.
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root boot
refer to a configuration where the operating