Opportunistic storage service

A service provider network, comprising:

• a plurality of servers;
• a computing service implemented via the servers, wherein the computing service is configured to:
• provision a compute instance to a client of the service provider network, wherein a compute component and a storage component of a given one of the servers are used to implement the compute instance and provision primary storage capacity for the compute instance;
• and
• a storage service implemented at least in part via the servers, wherein the storage service is configured to:
• receive a request to store a data object;
• store a first copy of the data object using currently unused provisioned primary storage capacity of the given one of the servers that implements the compute instance, wherein the unused provisioned primary storage capacity is provisioned as the primary storage capacity for the compute instance but is currently not being used to store data for the compute instance;
• and
• store a second copy of the data object using currently unused provisioned primary storage capacity of another one of the servers that implements another compute instance, wherein the unused provisioned storage of the other server is provisioned as primary storage capacity for the other compute instance but is currently not being used to store data for the other compute instance,
• wherein the storage capacity used to store the first and second copy of the data object comprise opportunistic storage capacity of the given server and the other server that is subject to revocation upon an additional portion of the provisioned primary storage capacity of the compute instance or the other compute instance being required to store data for the compute instance or the other compute instance.

A data storage service, comprising:

• one or more physical storage hosts;
• and
• one or more computing devices configured to:
• request opportunistic storage capacity from an opportunistic storage service to supplement storage capacity of the one or more physical storage hosts of the data storage service;
• store a data object in a storage of one of the physical storage hosts of the data storage service;
• and
• cause a first replica and a second replica of the data object to be stored using opportunistic storage capacity provisioned to the data storage service on a given server and another server associated with the opportunistic storage service.

One or more non-transitory, computer-readable storage media, storing program instructions that, when executed on or across one or more computing devices, cause the one or more computing devices to:

• identify currently unused provisioned primary storage capacity on physical storage components included in computing devices of a provider network;
• provision at least a portion of the currently unused provisioned primary storage capacity on the physical storage components as opportunistic storage capacity, wherein the opportunistic storage capacity is provisioned subject to revocation based on an additional portion of a given physical storage component being required to store data for a particular compute instance to which primary storage capacity on the given physical storage component is also provisioned;
• and
• store a plurality of copies of a data object using the provisioned opportunistic storage capacity.