CompTIA Security_ Deluxe Study Guide_ SY0-201 - Emmett Dulaney [208]
Disk duplexing is the same as disk mirroring except there is also a second controller. Fifty percent of the overall storage capacity must be used for RAID, so you must purchase four 500GB drives. This will give you excess data capacity of 200GB.
Scenario 2 Your primary server is currently running four 300GB disks in a RAID 5 array. Storage space is at a premium, and a purchase order has just been approved for four 500GB disks. Still utilizing a RAID 5 array, what is the maximum data storage space this server will be able to host?
The solution that will generate the most data storage capacity is to install all eight drives (the four current ones and the four new ones) into the server. The array must use the same size storage on each drive, thus all eight drives will appear as if they are 300GB drives. Under this scenario, 2100GB can be used for data storage and 300GB will be used for parity.
Scenario 3 Access speed is of the utmost importance on the web server. You want to purchase some fast 300GB hard drives and install them in a RAID 0 array. How many drives will you need to purchase to host 900GB of data?
RAID 0 doesn’t perform any fault tolerance and doesn’t require any extra disk space. You can obtain 900GB of data by using three disks.
You must do a fair amount of planning before you implement RAID. Within the realm of planning, you must be able to compute the number of disks needed for the desired implementation.
Disaster Recovery
Disaster recovery is the ability to recover system operations after a disaster. A key aspect of disaster-recovery planning is designing a comprehensive backup plan that includes backup storage, procedures, and maintenance. Many options are available to implement disaster recovery. The following sections discuss backups and the disaster-recovery plan.
It’s important to recognize that during a recovery, it may not always be necessary to immediately bring all systems and services back up. Critical systems should be the priority; extraneous services (such as an informational website for the public) can often be of lesser priority and attended to after everything else is up and running.
Depending on Backups
Backups are duplicate copies of key information, ideally stored in a location other than the one where the information is currently stored. Backups include both paper and computer records. Computer records are usually backed up using a backup program, backup systems, and backup procedures.
The primary starting point for disaster recovery involves keeping current backup copies of key data files, databases, applications, and paper records available for use. Your organization must develop a solid set of procedures to manage this process and ensure that all key information is protected. A security professional can do several things in conjunction with system administrators and business managers to protect this information. It’s important to think of this problem as an issue that is larger than a single department. The following are examples of key paper records that should be archived:
■ Board minutes
■ Board resolutions
■ Corporate papers
■ Critical contracts
■ Financial statements
■ Incorporation documents
■ Loan documents
■ Personnel information
■ Tax records
This list, while not comprehensive, gives you a place to start when you evaluate your archival requirements. Most of these documents can be easily converted into electronic form. However, keeping paper copies is strongly recommended because some government agencies don’t accept electronic documentation as an alternative to paper documentation.
Computer files and applications should also be backed up on a regular basis. Here are some example of critical files that should be backed up:
■ Applications
■ Appointment files
■ Audit files
■ Customer lists
■ Database files
■ E-mail correspondence
■ Financial data
■ Operating systems
■ Prospect