Server Availability
Information gathered from the previous specifications dictate the level
of availability that is required. The services are then classified using
the following availability classes.
|
SYSTEM-TYPE
|
AVAILABILITY CLASS |
UNAVAILABILITY MINUTES/YEAR |
SYSTEM AVAILABILITY |
|
Unmanaged
|
1 |
50,000
|
90%
|
|
Managed
|
2 |
5,000
|
99.0%
|
|
Well-Managed
|
3 |
500 |
99.9% |
|
Fault-Resilient
|
4 |
50 |
99.99% |
|
High-Availability
|
5 |
5 |
99.999% |
While the table represents system availability, it is important to note
that the figures represent unscheduled down time. It is critical that
“windows” are allowed for scheduled maintenance and upgrades. The down
time is always be scheduled on the same day every week over the weekend.
Many companies detail acceptable times during the weekend such as 11
p.m. Saturday to 2 p.m. Sunday. The specific time needs to be
negotiated.
The maximum allowable
scheduled down time per week for the Exchange systems should also be
defined. For example, you could specify an eight-hour maximum window
during the week and 25 hours one weekend per month.
You may want to send out a
user survey in order to determine the best time for scheduled
maintenance.
The
outsourcing vendor must balance the uptime requirements with the
inevitable cost. The foundation for a mission-critical architecture has
specifications for server availability, data accessibility, data
protection and disaster tolerance.
Access and Security
ABC Company should require
that named contacts be permitted physical access to the equipment at any
given time. Moreover, overall access to the equipment must be secured
and restricted. Access to the equipment must be available 24 hours a
day, 7 days per week for the vendor’s support personnel.
Disaster Recovery
Preparation
Backups
Many companies require that the clients be able to request a "recovery
of deleted items" for up to 30 days of deleted items. Moreover, backup
tapes to the system should be placed in a 30 day rotation, then erased
or destroyed. There should be no tapes that contain data over thirty
days old.
In
some cases, there may be a need to recover items from tape. The
outsourcing vendor should honor such a request from any of the named
contacts on the SLA. The outsourcing vendor may accept requests from the
user community for restores, but should then verify the request with the
named ABC Company contacts.
Monitoring
ABC Company does not have
any specific requirements in regards to the types of systems (software)
used to monitor the equipment.
Staffing
Certification and
Experience
ABC
Company requires that at least one person supporting the systems have
current MCSE status. At least two of the support personnel must be
certified on the current version of Microsoft Exchange Server.
Exclusive/Nonexclusive use
ABC
Company requires that the resources that support the ABC Company
Exchange systems be exclusive to ABC Company and not used for non-ABC
Company projects or tasks.
Equipment
Brand/Vendor
While ABC Company has no requirements as to the brands or types of
equipment used for the Exchange Server environment, ABC Company does
require that the equipment be included on the Hardware Compatibility
List for the current version of Microsoft BackOffice.
The
outsourcing vendor is responsible for the requisitions and costs
associated with all equipment necessary to support the ABC Company
Exchange Systems.
Spares for
testing/recovery
ABC
Company requires that at least two entire servers be allocated for spare
equipment and testing/recovery. The servers must match the current
servers in production so that parts can be swapped and/or replaced. ABC
Company further requires that the test equipment be updated as the
production equipment and online at all times for testing. |
