[id='xsite_compare_backups-{context}']
= Synchronous vs Asynchronous Backups
Synchronous backups offer the strongest guarantee of data consistency across
sites. If `strategy=sync`, when `cache.put()` calls return you know the value
is up to date in the local cache and in the backup locations.

The trade-off for this consistency is performance. Synchronous backups have
much greater latency in comparison to asynchronous backups.

Asynchronous backups, on the other hand, do not add latency to client requests
so they have no performance impact. However, if `strategy=async`, when
`cache.put()` calls return you cannot be sure of the value in the backup
locations is the same as in the local cache.
