Celerra
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Celerra is the family name for EMC's Network Attached Storage (NAS) controller products. Physically, a Celerra system occupies a full standard size rack enclosure and consists of one or two Celerra Control Stations, (shoebox-sized computers running EMC's hardened Linux variant), and one or more Celerra Data Movers (the "NAS heads"--shoebox-sized computers running the DART operating system that serve data).
The Celerra will typically control one or more storage systems, such as a CLARiiON or Symmetrix. The Celerra Data Movers are themselves SAN-attached to the storage system and take the place of an actual SAN attached server; they then present file shares to the network environment, typically using CIFS or NFS (other protocols such as FTP are also available). Beside the file sharing capabilities the Celerra can also provide iSCSI LUNs. The Celerra Data Movers have multiple copper gigabit Ethernet connections, for handling requests from multiple customer VLANs, and multiple HBAs, for moving large amounts of data to and from the storage systems or for backup traffic. Depending on model, each data mover can typically control between eight and sixteen TB of disk before beginning to degrade in responsiveness; different Celerra models have varying numbers of slots for data mover, but a fully-built Celerra NSX can present a maximum of approximately one hundred terabytes of storage and support thousands of simultaneous connections to users; to expand beyond this, multiple Celerras can be linked together and managed as a single system.
The Data Movers themselves have no administrative services presented on their customer-facing network interfaces; they are administered by the control station via a private back-end network. All administration is done through a Java-based graphical web interface, running on the control station, or through an SSH or telnet connection to the control station. This enhances the Celerra's security by effectively separating the administrative interface (control station) from the data interfaces (data movers), thus making it harder to exploit any security flaws in the DART OS and gain unauthorized access to the hosted data.
