CompTIA Security_ Deluxe Study Guide_ SY0-201 - Emmett Dulaney [214]
An important recovery issue is to know the order in which to progress. If a server is completely destroyed and must be re-created, ascertain which applications are the most important and should be restored before the others. Likewise, which services are most important to the users from a business standpoint and need to be available? Conversely, which are nice but not necessary to keep the business running? The answers will differ for every organization, and you must know them for yours.
Planning for Alternate Sites
Another key aspect of a disaster-recovery plan is to provide for the restoration of business functions in the event of a large-scale loss of service. You can lease or purchase a facility that is available on short notice for the purpose of restoring network or systems operations. These are referred to as alternate or backup sites.
Another term for alternate site is alternative site; the terms are often used interchangeably.
If the power in your local area were disrupted for several days, how would you reestablish service at an alternate site until primary services were restored? Several options exist to do this; I’ll briefly present them here. None of these solutions are ideal, but they are always considered to be significantly less costly—in terms of time—to implement than the estimated time of bringing your original site back up to speed. They are used to allow you to get your organization back on its feet until permanent service is available. An alternative site can be a hot site, a warm site, or a cold site:
Hot site A hot site is a location that can provide operations within hours of a failure. This type of site would have servers, networks, and telecommunications equipment in place to reestablish service in a short time. Hot sites provide network connectivity, systems, and preconfigured software to meet the needs of an organization. Databases can be kept up-to-date using network connections. These types of facilities are expensive, and they’re primarily suitable for short-term situations. A hot site may also double as an offsite storage facility, providing immediate access to archives and backup media.
A hot site is also referred to as an active backup model.
Many hot sites also provide office facilities and other services so that a business can relocate a small number of employees to sustain operations.
Given the choice, every organization would choose to have a hot site. Doing so is often not practical, however, on the basis of cost.
Warm site A warm site provides some of the capabilities of a hot site, but it requires the customer to do more work to become operational. Warm sites provide computer systems and compatible media capabilities. If a warm site is used, administrators and other staff will need to install and configure systems to resume operations. For most organizations, a warm site could be a remote office, a leased facility, or another organization with which yours has a reciprocal agreement.
Another term for a warm site/reciprocal site is active/active model.
Warm sites may be for your exclusive use, but they don’t have to be. A warm site requires more advanced planning, testing, and access to media for system recovery. Warm sites represent a compromise between a hot site, which is very expensive, and a cold site, which isn’t preconfigured.
An agreement between two companies to provide services in the event of an emergency is called a reciprocal agreement. Usually, these agreements are made on a best-effort basis: There is no guarantee that services will be available if the site is needed. Make sure your agreement