Backups
How much backup storage do you actually need?
Backup capacity is not the same as live disk capacity. A server using 700 GB does not automatically need a 700 GB backup destination, and a 2 TB server does not automatically need 2 TB. Retention and how much the data changes matter just as much.
Start with the data that actually needs protection
Measure the files, databases, configuration, mail, and application state you need to restore. Temporary files, caches, package downloads, logs with another retention path, and reproducible build artifacts may not need to be included.
Add room for versions
If you only keep one current copy, storage can be close to the protected data size. If you keep daily, weekly, or monthly restore points, you need capacity for changes between versions. Incremental and deduplicated backup systems can reduce this substantially.
Account for change rate
A mostly static 1 TB archive behaves very differently from a 1 TB database or media workload that changes heavily every day. Measure how much new or modified data is produced over a normal week before choosing a retention target.
Compression helps, but do not depend on a perfect ratio
Databases, text, and some application files may compress well. Photos, video, encrypted data, and already-compressed archives often do not. Plan capacity from observed backup sizes rather than a best-case estimate.
Leave growth and recovery headroom
A destination that is constantly near full is difficult to operate safely. Leave enough room for data growth, a larger-than-normal backup, temporary restore work, and changes to retention.
A practical starting point
If you protect hundreds of gigabytes and keep several restore points, 1 TB may be enough. Larger VPSs, multiple servers, media collections, or longer retention can justify 2 TB or 4 TB quickly. Measure the first real backup and adjust from there.