Home  ›  Glossary  ›  Backup Window

What is a backup window?

A backup window is the period when backup jobs are allowed to run, usually overnight or at weekends when systems are quiet.

Packing everything into the small hours has a cost. Acronis studied about 960 million backup jobs in an analysis published in 2026. Full backups started at 2 a.m. failed more than five times as often as those started at 6 a.m.

A moving van with a deadline

Picture a removal crew that has to empty a house between midnight and 6 a.m. The van, the crew and the narrow staircase all have limits. Whichever is slowest decides whether the job is done by morning.

Backup jobs work the same way. Data passes through the source disks, the backup server, the network and finally the backup target. The slowest of these sets the pace. And while the night stays the same length, the amount of data to move grows every year.

What crowds the night

Nightly copies of changed data rarely cause trouble on their own. The squeeze comes from everything else booked into the same hours: weekly full backups, copies to a second site, health checks and clean-up of expired data. Service providers feel it most, because many customers pick the same late-evening slot.

Several techniques take pressure off the source systems. A synthetic full backup builds the weekly full from data already in storage. Continuous data protection copies each change as it happens, so there is no nightly rush at all. Neither one removes the work the storage itself has to do.

Signs the window no longer fits

  • Jobs are still running when staff log in, and users notice slow systems.
  • A large server has quietly been moved to weekend-only backups.
  • Copy jobs to a second site or locked storage are skipped on busy nights.
  • A file share was excluded "until someone has time to look at it".
  • Job times creep up a little every week.

Each of these leaves a gap in restore points that no one sees until a restore needs one. A schedule that fits also says nothing about recovery. Reading a whole estate back after ransomware is a far bigger job, limited by restore throughput. The bigger picture sits under data backup.

ARTESCA and backup window

As the S3 target, ARTESCA is one of the stages that decides whether the night fits. The throughput it sustains depends on its setup: the number of servers and drives, the network and how many jobs write at once.

Storage load shows in the ARTESCA management interface and through Grafana and Prometheus metrics. Those figures can be lined up against job times from the backup application when a window starts to slip. Which jobs run, and when, stays a decision of the backup application.