Administrator Guide

Software and upgrade
This chapter describes the GeoSynchrony software that runs on the metro node hardware.
Topics:
• Metro node OS
• Non-disruptive upgrade (NDU)
Metro node OS
Metro node OS is the operating system that runs on the metro node hardware.
Metro node OS is:
● Designed for highly available, robust operation in geographically distributed environments
● Driven by real-time I/O operations
● Intelligent about locality of access
● Designed to provide the global directory that supports AccessAnywhere
The following table summarizes features provided by metro node OS and AccessAnywhere:
Table 4. Metro node OS AccessAnywhere features
Feature Description and considerations
Storage volume encapsulation LUNs on a back-end array can be imported into an instance of
metro node and used while keeping their data intact.
Considerations: The storage volume retains the existing data
on the device and leverages the media protection and device
characteristics of the back-end LUN.
RAID 1 metro node devices can be mirrored within a site.
Considerations: Withstands a device failure within the
mirrored pair.
● A device rebuild is a simple copy from the remaining
device to the newly repaired device. Rebuilds are done in
incremental fashion, whenever possible.
● The number of required devices is twice the amount
required to store data (actual storage capacity of a
mirrored array is 50%).
● The RAID 1 devices can come from different back-end
array LUNs providing the ability to tolerate the failure of
a back-end array.
Distributed RAID 1 Metro node devices can be mirrored between sites.
Considerations: Provides protection from site disasters and
supports the ability to move data between geographically
separate locations.
Migration Volumes can be migrated non-disruptively to other storage
systems.
Considerations: Use migration for changing the quality of
service of a volume or for performing technology refresh
operations.
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30 Software and upgrade