Backup Policy
Purpose
It is the policy of IT Services to provide centralised system backups of core servers/services to tape on a regular basis. The IT Service Delivery Group is responsible for implementing this policy. This page outlines what the policy means, and what benefits and costs accrue.
Philosophy
The backup system is designed to recover from "catastrophic loss," meaning complete destruction of a server, set of servers (services), or the entire site. It also covers disk hardware failure, where only part of a system needs recovery. The purpose is disaster recovery as opposed to covering for user mistakes.
A side effect of the backup system is the ability, in many cases, to restore individual files or sets of files for individual users. Doing this takes some time, thus priorities must be considered. Users are urged to ensure that their actions will bring about the desired results before pressing that last keystroke.
Assumptions
It is assumed that:
- the various schools and professional services, and thus total disk storage, will continue to expand at a rate similar to what has been taking place over the past years;
- the schools and support services will remain heterogeneous in computing equipment types, and that the heterogeneity is likely to increase, with all platforms requiring support.
Scope
The University central servers cover some 6 terabytes of disk, which will probably grow during the following 12 months. The intent is to have the backup system cover all production equipment, allowing a complete business resumption in case of loss of the entire site. Non central data storage amounts to a further 300 gigabytes of disk comprised entirely of user data, some backed up from central systems, the majority using distributed media devices. All server platforms managed by IT Services are to be eligible. Additional platforms may be covered as negotiated with IT Services. Any queries please use Self Service to log a job yourself or phone 65515.
Special Functions
The backup system may occasionally be used for other functions. It is common for staff members to request custom preparation of tapes for shipment, or to store a set of files long term. These functions will be supported, but at a fee to the project or user.
Scheduling
A complete current backup set will be moved into fireproof storage at least once per week. Incremental capability to restore those sets to more current status will be accomplished on approximately an every-workday-evening basis. A complete backup set will be retained for a minimum of two months. Incremental sets will be maintained for a minimum of one month.
Backups will generally be performed at night and on weekends (local times). On occasion, particularly when a run fails, IT Services will perform one or more backups during workdays, but these will be done with a goal of minimizing impact on users while accomplishing the backup, and only when necessary.
This schedule means that not all files will be recoverable at any given time. Services can be restored to the status they were in on a given day at the time the backup was initiated. Any files created (or versions of files modified) after one backup ran then modified or deleted prior to the next run will not be restorable. Files not present at the time of a monthly backup will not be recoverable after the incremental tapes are recycled (generally a few months later).
Restorations
Systems/services requiring recovery from disk damage or other catastrophic loss will be restored as best possible at high priority bases on the current IT Continuity Plans. User file restorations will be handled as time permits.
Verification
At scheduled intervals, typically once per week the backup system will be tested by restoring a single random file from a random machine, and manually inspecting it for accurate restore capabilities. Typically once per month a similar test will be made using an entire directory. These restore tests will be performed into temporary areas so that current "real" user copies of the files will not be overwritten. The form of manual inspection will vary with the type of file(s) restored. Text may be "diff"ed or inspected manually. Binaries may be binary "diff"ed where the tape copy is still current, may be run in some cases, or may be dumped in hexadecimal format for manual comparison.
