The Unofficial Backup Admin's Handbook Part 3
As the name implies, schedules dictate the frequency a particular backup operation occurs. They can be as short as minutes, or can span to years. The most common schedule frequencies are:
Jobs that run with a frequency of a certain number of hours. Not commonly used for file system jobs, they are know more for application backup jobs such as SQL transaction logs.
Backup job runs once per day. These are used for frequent jobs, such as an incremental you want to run everyday. They are also commonly used for more critical application backup jobs, such as a SQL database that you want a full backup of every day.
Backup job runs once per week. This job is typically on the same day each week, and are commonly used to run larger backups. An example would be running a Full backup every Saturday.
Backup job runs once per month, typically on a designated day, such as the first or last day of the month, or on a particular day, such as the first Saturday. These usually have a longer retention period and are more commonly broken out for some sort of compliance requirements. They are commonly scheduled to coincide with events such month end reporting.
These are usually further divided into "backup windows", period of time in which backup operations can kick off and run. Backup windows are typically "opened" (allowed to begin) during times of lower utilization of the system, such as when a business is closed.
Many backup products will allow you to decide the behavior for when a backup window "closes". If the job is scheduled but not running it may simply kill the job. If it's running it can either allow it to run to completion or terminate the job and end the job with an error.
Your frequency and backup types are commonly based around Recovery Point Objectives (RPO) and Recovery Time Objectives (RTO). You may decide that your system needs daily full backups because it is a critical server. It may be a common file server of low importance and you deem a Weekly Full backup with Daily Incrementals is acceptable.
Recovery Point Objectives can be thought of as "how much data am I willing to lose and must be recreated". This would be how much time can occur between backup operations.
Recovery Time Objectives would be "how long am I willing to be without my data". This determines how much time can be taken to perform any/all restores required (such as Full + all Incremental backups).
RPO and RTO will also be used to determine which type of backup medium will need to be used, or if the system needs to be configured in another method to allow for continuous operations (such as mirroring, clustering, log shipping, etc).
Part 4: Storage Mediums
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