About filers

What a filer is

A filer is a hardware and software storage system that serves data. It acts on network requests from clients and processes them by writing data to or retrieving data from disks in disk shelves that are connected to it. The software that enables the filer to perform these tasks is the Data ONTAP operating system.

Components of a filer

A filer consists of the following major components.

Component	Function	To learn more, read...
Filer main unit, or chassis	The piece of hardware that receives and sends data	About filer main unit components
Disk shelves	Hardware that holds disks and is connected to the filer	About disk shelves
Data ONTAP	Software that is the operating system for the filer	About Data ONTAP

Note
Model FAS250, FAS270 and FAS 270c filers combine the filer head or heads and disk shelf into one unit.

What a filer does

A filer provides the following features.

Feature	Description
Network file service	The filer enables users on client workstations (or hosts) to create, delete, modify, and access files or blocks stored on it. Client workstations are connected to the filer through TCP/IP, direct-attached, or fabric-attached network connections.
Multiprotocol file and block sharing	Clients can use the following protocols to access data on the filer: CIFS (Common Internet File System)--used by Windows® clients FCP (Fibre Channel Protocol)--used for block access in storage area networks DAFS (Direct Access File System)--used by DAFS clients HTTP (HyperText Transfer Protocol)--used by the World Wide Web iSCSI (Internet small computer system interface)--used for block access in storage area networks NFS (Network File System)--used by UNIX systems (PC)NFS (Personal Computer NFS)--used by PCs to access NFS Files written through one protocol are accessible to clients of any protocol, provided that filer licenses and permissions allow it. For example, an NFS client can access a file created by a CIFS client, and a CIFS client can access a file created by an NFS client. Blocks written through one protocol can also be accessed by clients using the other protocol.
Data protection	The filer protects disk data in the following ways: Snapshot^TM same-volume backup enables you to manually or automatically create, schedule, and maintain multiple backups (or snapshots) of volume and qtree images, using only a minimal amount of additional volume space at no performance cost. SnapMirror® (license required) filer-to-filer snapshot mirroring enables you to mirror snapshots on one filer to a partner filer. Should the original filer be disabled, this ensures quick restoration of data from the point of the last snapshot. SnapVault^TM (license required) multiple-sources-to-central-system snapshot backup backs up snapshots from qtrees on multiple volumes and filers to a single Network Appliance SnapVault secondary storage system. This system is specialized for quick backup and restore of its filer sources. The SnapRestore® (license required) software feature performs fast restores of backed-up data on request from snapshots on an entire volume. Tape backup dump and restore commands enable you to back up filer or SnapVault snapshots to tape. Because the snapshot rather than the active file system is backed up to tape, the filer can continue its normal functions while the tape backup is still in operation. Vol copy (license required) fast block copy of data enables you to quickly copy blocks of stored filer data from one volume to another.
Data protection (continued)	The SyncMirror^TM feature performs real-time mirroring of data to two separate filer volumes physically connected to the same filer head. In case of multiple unrecoverable disk errors on one volume, the filer automatically switches access to the mirrored volume. NDMP (Network Data Management Protocol) support enables third-party applications that use NDMP to manage tape backup operations of filer data. The NDMP `copy` command carries out NDMP-compliant backups and restores. Security login restricts access to NDMP operations. The `nvfail` option provides protection against data corruption by nonvolatile RAM (NVRAM) failures.
Autosupport	Mail notifications about filer problems are automatically sent to Network Appliance Technical Support.