Dell Fluid File System

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Dell Fluid File System, or FluidFS, is the result of Dell acquiring intellectual property from Exanet, Ltd. Exanet was a firm whose assets included a hardware-independent, scalable NAS storage solution. Previously known as the Dell Scalable File System (DSFS), Dell changed the name to FluidFS after its acquisition of Compellent, which successfully used the Fluid Data tag-line as a startup company.[1] Dell further developed the Exanet file system to support NDMP backup and integrated it with the IP obtained from the acquisition of Ocarina Networks, which included deduplication and compression technology. Dell initially adapted FluidFS to work with its Compellent, EqualLogic, and PowerVault storage platforms.[2]


Top to bottom: Users connect via the "front-end" to NAS appliances running FluidFS, which connect through "back-end" switches to disk arrays.

FluidFS is a shared-disk filesystem that provides distributed file systems to clients. Customers buy an appliance: a combination of purpose-built NAS controllers with integrated primary and backup power supplies (i.e., the appliance) attached to block level storage via the iSCSI or Fiber Channel protocol. A single Dell FluidFS appliance consists of two controllers operating in concert (i.e., active/active) connecting to the back-end storage area network (SAN). Depending on the storage capacity requirements and user preference, FluidFS version 3 NAS appliances can be used with Compellent, EqualLogic or PowerVault SAN arrays. The EqualLogic FS7600 and FS7610 connect to the client network and to Dell's EqualLogic arrays with either 1 Gbit/s (FS7600) or 10 Gbit/s (FS7610) iSCSI protocol. For Compellent, FluidFS is available with either 1 Gbit/s or 10 Gbit/s iSCSI connectivity to the client network and connection to the backend Compellent SAN can be either 8 Gbit/s Fibre Channel or 10 Gbit/s iSCSI. The FluidFS software layer running on the NAS Appliance creates a single name-space to the users, offering access via CIFS and Network File System (NFS). It also includes features to prevent data-loss or corruption and uses caching to increase performance.[2]


The underlying software architecture of FluidFS leverages a symmetric clustering model with distributed metadata, native load balancing, advanced caching capabilities and a rich set of enterprise-class features. FluidFS removes the scalability limitations such as limited volume size associated with traditional file systems and supports high capacity, performance-intensive workloads via scaling up (adding capacity to the system) and by scaling out (adding nodes, or performance, to the system.FluidFS operates across a symmetric cluster of purpose-built NAS controllers (housed in pairs within a 2U appliance), which interface over a fabric to shared back-end storage via iSCSI or Fibre Channel storage area networks.

The FluidFS architecture approaches layering with performance in mind. The layered architecture presents a traditional file system to network clients while performing a range of special functions at the back end. The specific goal of this design is to utilize all available resources at the network, server and disk levels to support the fastest possible response times.


Based on the back-end storage solution the maximum number of NAS appliances and storage capacity varies. The number of NAS appliances varies from 1 to 4. The total storage capacity of the system varies between a few TB to 2 PB (Fluid FS v3 with FS8600). The entire capacity of the system can be managed in a single namespace. The maximum size of any single file is 4 TB. The number of files the name-space is limited to 64 billion per appliance or 256 billion in 4 appliances making it one of the largest in the industry.


  1. ^ Compellent website on Dell Compellent and the Dell Fluid Data, visited 10 December 2012
  2. ^ a b Technology Whitepaper: Dell FluidFS, June 2013. Visited: 6 December 2013