This page details R2’s consistency model, including where R2 is strongly, globally consistent and which operations this applies to.
R2 can be described as “strongly consistent”, especially in comparison to other distributed object storage systems. This strong consistency ensures that operations against R2 see the latest (accurate) state: clients should be able to observe the effects of any write, update and/or delete operation immediately, globally.
In the context of R2, strong consistency and eventual consistency have the following meanings:
- Strongly consistent - The effect of an operation will be observed globally, immediately, by all clients. Clients will not observe ‘stale’ (inconsistent) state.
- Eventually consistent - Clients may not see the effect of an operation immediately. The state may take a some time (typically seconds to a minute) to propagate globally.
Operations and Consistency
Operations against R2 buckets and objects adhere to the following consistency guarantees:
- In the event two clients are writing (
DELETE) to the same key, the last writer to complete “wins”.
- When performing a multipart upload, read-after-write consistency continues to apply once all parts have been successfully uploaded. In the case the same part is uploaded (in error) from multiple writers, the last write will win.
- Copying an object within the same bucket also follows the same read-after-write consistency that writing a new object would. The “copied” object is immediately readable by all clients once the copy operation completes.
Specifically, you should expect:
- An object you delete from R2, but that is still cached, will still be available. You should after deleting objects if you need that delete to be reflected.
- By default, Cloudflare’s cache will automatically. If you upload an object to that same path, the cache may continue to return HTTP 404s until the cache TTL (Time to Live) expires and the new object is fetched from R2 or the .
- An object for a given key is overwritten with a new object: the old (previous) object will continue to be served to clients until the cache TTL expires (or the object is evicted) or the cache is purged.