Whereas entire files are stored in a folder system in the case of file storage, for example, block storage stores data in the form of blocks in a location regarded as the most suitable by the system. In this process, the files are split evenly into blocks. The files therefore lose their actual meaning and cannot be readily executed or opened. Blocks are units of the same size. In order to retrieve the individual blocks, an address is assigned to each of them. If the server receives a request, it can locate the files, merge them back together and then deliver them.
Block storage is usually implemented in a Storage Area Network (SAN). Here, several servers have access to data storage through a network. This is all controlled by a software program that locates the blocks. Although block storage in an SAN was originally set up like a LAN with switches and hubs, now it can also be implemented in cloud environments. We usually call this block-level storage. This simulates an interrelated system comprising hard drives as would have been used traditionally.
In an SAN, a Fiber Channel (FC) or Internet Small Computer System Interface (iSCSI) is normally used for communication. An FC is an interface that was developed for ultra-fast transmission. However, the iSCSI method uses TCP and Ethernet and can therefore be easily integrated into existing networks.