Data ONTAP storage architecture overview

Storage architecture refers to how Data ONTAP provides data storage resources to host or client systems and applications. Data ONTAP distinguishes between the physical layer of data storage resources and the logical layer.

•	The physical layer includes drives, array LUNs, virtual disks, RAID groups, plexes, and aggregates.

Note: A drive (or disk) is the basic unit of storage for storage systems that use Data ONTAP to access native disk shelves. An array LUN is the basic unit of storage that a storage array provides to a storage system that runs Data ONTAP. A virtual disk is the basic unit of storage for a storage system that runs Data ONTAP-v.

•	The logical layer includes the file systems—volumes, qtrees, logical unit numbers (LUNs)—and the directories and files that store data.

Note: LUNs are storage target devices in iSCSI and FC networks.

Aggregates provide storage to volumes. Aggregates can be composed of either drives or array LUNs, but not both. Data ONTAP organizes the drives or array LUNs in an aggregate into one or more RAID groups. RAID groups are then collected into one or two plexes, depending on whether RAID-level mirroring (SyncMirror) is in use. Aggregates can have two formats: 32-bit and 64-bit. An aggregate's format affects its maximum size.

Volumes are data containers. Clients can access the data in volumes through the access protocols supported by Data ONTAP. These protocols include Network File System (NFS), Common Internet File System (CIFS), HyperText Transfer Protocol (HTTP), Web-based Distributed Authoring and Versioning (WebDAV), Fibre Channel (FC), and Internet SCSI (iSCSI).

You can partition volumes and control resource usage using qtrees. You can create LUNs for use in a SAN environment, using the FC or iSCSI access protocols. Volumes, qtrees, and LUNs contain directories and files.

Parent Topic: Storage window