In computing (specifically data transmission and data storage), a block, sometimes called a physical record, is a sequence of bytes or bits, usually containing some whole number of records, having a maximum length, a block size. Data structured in this way are said to be blocked.
Most file systems are based on a block device.
Block storage is normally abstracted by a file system for use by applications and end users. The physical or logical volumes accessed via block I/O may be devices internal to a server, directly attached via SCSI or Fibre Channel, or distant devices accessed via a storage area network (SAN) using a protocol such as iSCSI, or AoE.
In City Cloud the following block storages are available: