This page describes per-object storage classes, as well as which per-object storage classes are available for different buckets. For examples of setting storage classes for objects, see Changing Object Storage Classes.
Per-object storage classes allow you to assign specific storage classes to individual objects within a bucket. When you upload an object, you can optionally specify a storage class for it. You can also change the storage class of an object that already exists in your bucket without moving the object to a different bucket or changing the URL to the object.
Setting a per-object storage class is useful, for example, if you have objects in your bucket that you want to keep, but that you don't expect to access frequently. In this case, you can minimize costs by changing the storage class of those specific objects to Nearline Storage or Coldline Storage.
Default bucket storage classes
If you don't specify a storage class for your object at the time of upload, the object is given the default storage class for the bucket. This default storage class for the bucket is set, either explicitly by you or automatically, when you create the bucket.
You can change the default storage class of a bucket. Note, however, that when you do, existing objects within the bucket keep their existing storage class.
For example, say you create a bucket with a default storage set to Multi-Regional Storage. Say you then upload an image to your bucket without specifying a storage class for it. That object is stored as Multi-Regional Storage. If you change the default storage class of your bucket to Nearline Storage, your image is still stored as Multi-Regional Storage.
The storage class that you can set for an object depends on the location
where the bucket that holds the object exists. Specifically, objects in
multi-regional locations such as
us can have a
Multi-Regional Storage, Nearline Storage, or Coldline Storage
class, while objects in regional locations such as
can have a Regional Storage, Nearline Storage, or Coldline Storage class.
For example, if you create a Nearline Storage bucket in
can use per-object storage classes to change the storage class of individual
objects in the bucket to Regional Storage or Coldline Storage. Since
us-central1 is a regional location, you cannot change the storage
class of objects in the bucket to Multi-Regional Storage, nor can you
change the default storage class of the bucket to Multi-Regional Storage.
Changing per-object storage class automatically
In order to help manage the classes of objects in your bucket, Cloud Storage offers Object Lifecycle Management. This tool allows you to define rules that automatically transition your objects to cheaper storage classes when they meet criteria you've defined. To learn more, see the Object Lifecycle Management page.