Storage in Cloud

File System is a critical part in OS as it contains both OS, application binaries as well as application data. In traditional OS, it is usually on a hard disk or SAN attached disk. In cloud, there are more types of storage available.

Object Storage(examples: OpenStack swift, Amazon S3, Rackspace Cloud Files, Ceph Storage)

Object storage is the technology that store the files in ‘cloud’, usually the client can have access/modify to the file via HTTP interface(RESTful API), Application can build up file-level access based on object storage.

Block Storage(examples: nova-volume, Amazon ESB, iSCSI)

Block device is very similar to the SAN storage,  it exposed through a low-level computer bus interface which can be accessed over the network. The OS can create partitions and format the partitions to make the file system. the block Storage can usually only be attached to just one virtual server.

File Storage(examples:  NFS, CIFS, ClusterFS)

File Storage is quite similar to NAS,  client access data through OS’s file system level. Users access it by mouting a remote file system. usually the client need to install some software to remote access it.