SEASnet Backup and Tape Storage Retention Policies
The following policies govern data retention on SEASnet servers and user machines that receive backup support. These policies apply to both email and filesystem data for faculty and staff. The goal is to ensure that accidentally deleted data can be recovered for a reasonable period while providing a clear timetable for data retention. SEASnet aims to balance the need for recoverable data with ensuring that data is not retained longer than necessary.
Policy Overview
SEASnet provides snapshots of data stored on its servers. Snapshots are taken at regular intervals throughout the day (see schedule below). These snapshots allow users to restore accidentally deleted files without SEASnet intervention. Snapshots are retained for approximately 1–2 weeks. Instructions for restoring deleted files can be found here.
Backup Schedule
Home directories, Maildir and other filesystems
| Backup Level | Frequency | Storage | Retention |
|---|---|---|---|
| Full backup | Monthly | Tape | 6 months |
| Differential | Weekly | Tape | 3 months |
| Incremental* | Daily (Mon-Fri) | Disk | 4 weeks |
*PC backups are excluded from incremental backups.
These retention periods are not a guarantee that data will never be retained longer, either intentionally or accidentally.
Snapshot Schedule
File systems on NetApp filers (including Maildir and other filesystems):
| Snapshot Type | Snapshot Time | Storage | Retention |
|---|---|---|---|
| Hourly Snapshot | Every 2 hours (9am-11pm) | Disk (.snapshot) | 1 day |
| Daily Snapshot | Midnight (Mon-Sat) | Disk (.snapshot) | 8 days |
| Weekly Snapshot | Midnight (Sun) | Disk (.snapshot) | 2 weeks |
Again, retention beyond these periods may occur, either intentionally or accidentally.
Definitions
| Differential | Captures changes to files since the last full backup. Combined with a full backup, it allows for a complete restoration of the filesystem. |
| Full Backup | A backup of all data in the filesystem, enabling full restoration to the time of the backup. |
| Snapshots | Virtual images of a filesystem at specific times, allowing data retrieval up to the retention period. |