In order to understand the Minimum Storage Duration, it is necessary to know the concept of Storage classes first.
What is a storage class?
The storage class of an object or bucket affects the object's/bucket's
availability and pricing.
Depending on one's use case and how frequently one accesses the data in a bucket, he may chooce one of the available Storage Classes:
Standard Storage is used for data that is frequently accessed and/or
stored only for short periods of time.
Nearline Storage is a low-cost option for accessing infrequently
data. It offers lower at-rest costs in exchange to lower availability,
30 days minimum storage duration and cost for data access. It is
suggested to be used in use cases where one accesses his data once per
month on average.
Coldline Storage is similar to Nearline, but offers even lower
at-rest costs again in exhange to lower availability, 90 days minimum
storage duration and higher cost for data access.
Archive Storage is the lowest-cost, highly durable storage service
for data archiving, online backup, and disaster recovery. has no
availability SLA, though the typical availability is comparable to
Nearline Storage and Coldline Storage. Archive Storage also has higher
costs for data access and operations, as well as a 365-day minimum
storage duration.
You may find detailed information in the Storage Classes documentation.
So what is the minimum storage duration?
A minimum storage duration applies to data stored using one of the above storage classes. You can delete the file before it has been stored for this duration, but at the time of deletion you are charged as if the file was stored for the minimum duration.
Please note that minimum storage duration doesn't have to do with automatic deletion of objects.
If you would like to delete objects based on conditions such the Age of an object, then you may set an Object Lifecycle policy for the target object. You may find an example on how to delete live versions of objects older than 30 days, here.
