Microsoft Office Tutorials and References
In Depth Information
Built-in archiving is a new Exchange 2010 capability and is built as part of Exchange Online.
It can also be deployed as an independent workload, which we will see in greater detail
later in this chapter. Hosted archiving is known as EOA.
One of the biggest benefits of EOA is the ability to provision a large amount of storage
space for archiving purposes. Archiving, built into Exchange Online Plan 1, allows you to
provision an archive storage space that is part of a 25 GB mailbox. However, archiving in
Exchange Online Plan 2 or implemented as an independent workload gives you unlimited
archiving storage space.
INSIDE OUT Interpreting unlimited storage in EOA
When you provision archiving in Exchange Online Plan 2, even though the service touts
unlimited storage, in reality only 100 GB per mailbox is initially provisioned. The reason
for this is because EOA requires a valid size value, and zero, which is traditionally used
to indicate unlimited size, is not a valid value and the field cannot be blank. Therefore,
Microsoft Online Services chose 100 GB as an arbitrary high number. The service is still
intended to be unlimited, so if any of your users reach the 100 GB limit, you will simply
need to submit a service request to increase the limit. There will be no charge for any
additional storage beyond the 100 GB limit. Secondly, it is important to note that size
limit is separate from time limits. There is no time-limit dimension in EOA. Time limits
are based on the Message Records Management (MRM) capabilities of Exchange Online.
MRM leverages retention tags and retention policies to automatically delete messages.
Without a defined MRM, EOA will retain all messages in the primary mailbox and in EOA
unless a user manually deletes them.
Backup and recovery
EOA shares the same SLA as Exchange Online when it comes to service continuity and
disaster recovery. Like Exchange Online, EOA backups are for disaster recovery purposes
and not designed to respond to service requests for single-item recovery. All EOA recovery
capabilities are based on the same Exchange Online recovery capabilities covered in the
Exchange Online section earlier in this chapter. EOA provides 99.9 percent guaranteed
service availability; the same one hour RTO and almost instantaneous RPO also apply.