Cloud Storage Gateway (CSG) is a gateway that can be deployed in your IDC and on your Alibaba Cloud products. It uses Alibaba Cloud Object Storage Service (OSS) buckets as backend storage devices and provides on- and off-cloud applications with standard file services through the Network File System (NFS) and Common Internet File System (CIFS) protocol and block storage services through the Internet Small Computer Systems Interface (iSCSI) protocol.
CSG supports two types of gateways:
• File gateway
File gateway uses OSS buckets as backend storage devices and maps the object directory structure of OSS buckets to the file system of Network Attached Storage (NAS). The CSG client can read and write all objects in an OSS bucket through the standard NFS and CIFS protocols. In addition, CSG provides higher bandwidth and lower latency, especially for the read/write performance of small files, and improves the compatibilities with the Portable Operating System Interface (POSIX) and third-party backup software. This type of gateway applies to enterprises with high performance and enterprise compatibility requirements.
• Block gateway
Block gateway creates storage volumes in OSS buckets and support block-level access through the iSCSI protocol. Local applications can access the volumes as the iSCSI targets. Block gateway provides the write-through and cache modes. In write-through mode, the data in block volumes is sliced and synchronized to the cloud. This mode applies to users who use high-speed links such as leased lines. In cache mode, ephemeral disks can be created for read/write acceleration and for asynchronization of data to the cloud. This mode applies to users who expect fast local access but use slow cloudification links.