ONTAP, Data ONTAP, Clustered Data ONTAP (cDOT), or Data ONTAP 7-Mode is NetApp's proprietary operating system used in storage disk arrays such as NetApp FAS and AFF, ONTAP Select, and Cloud Volumes ONTAP. With the release of version 9.0, NetApp decided to simplify the Data ONTAP name and removed the word "Data" from it, removed the 7-Mode image, therefore, ONTAP 9 is the successor of Clustered Data ONTAP 8.
ONTAP originally only supported NFS, but later added support for SMB, iSCSI, and Fibre Channel Protocol (including Fibre Channel over Ethernet and FC-NVMe).
The original version of ONTAP had a proprietary non-UNIX kernel and a TCP/IP stack, networking commands, and low-level startup code from BSD Net/2 and 4.4BSD-Lite.
On June 16, 2006, NetApp released two variants of Data ONTAP, Data ONTAP 7G and, with nearly a complete rewrite, Data ONTAP GX. Data ONTAP GX was based on grid technology acquired from Spinnaker Networks, and boots from FreeBSD as a stand-alone kernel-space module and uses some functions of FreeBSD (for example, it uses a command interpreter and drivers stack).
In 2010 these software product lines merged into one OS - Data ONTAP 8, which folded Data ONTAP 7G onto the Data ONTAP GX cluster platform. Data ONTAP 8 includes two distinct operating modes held on a single firmware image. The modes are called ONTAP 7-Mode and ONTAP Cluster-Mode. The last supported version of ONTAP 7-Mode issued by NetApp was version 8.2.5. All subsequent versions of ONTAP (version 8.3 and onwards) have only one operating mode - ONTAP Cluster-Mode.
Data ONTAP was made available for commodity computing servers with x86 processors, running atop VMware vSphere hypervisor, under the name "ONTAP Edge". Later ONTAP Edge was renamed to ONTAP Select and KVM was added as a supported hypervisor.
NetApp storage arrays use highly customized hardware and ONTAP, both originally designed by NetApp founders David Hitz and James Lau specifically for storage-serving purposes. All storage array hardware includes battery-backed non-volatile memory, which allows them to commit writes to stable storage quickly, without waiting on disks. ONTAP is also used for virtual storage appliances (VSA), such as ONTAP Select and Cloud Volumes ONTAP, both of which are based Data ONTAP Edge; virtual storage appliances use virtual nonvolatile memory
Implementers often organize two storage systems in a high-availability cluster with a private high-speed link, either a Fibre Channel, InfiniBand, 10 Gigabit Ethernet, 40 Gigabit Ethernet, or 100 Gigabit Ethernet. One can additionally group such clusters under a single namespace when running in the "cluster mode" of the Data ONTAP 8 operating system or on ONTAP 9.
History Data ONTAP, including WAFL, was developed in 1992 by David Hitz, James Lau, and Michael Malcolm. Initially, it supported NFSv2; the CIFS protocol was introduced to Data ONTAP 4.0 in 1996. In April 2019, Octavian Tanase SVP ONTAP posted a preview photo on his Twitter of ONTAP running in Kubernetes as a container for a demonstration.
WAFL File System
The Write Anywhere File Layout (WAFL) is a file layout used by ONTAP OS that supports large, high-performance RAID arrays, quick restarts without lengthy consistency checks in the event of a crash or power failure, and growing the size of the filesystems quickly.
Storage efficiency
ONTAP OS contains several storage efficiencies, which are based on WAFL functionalities. Supported by all protocols, does not require licenses. In February 2018 NetApp claims AFF systems for its clients gain an average of 4.72:1 Storage Efficiency from deduplication, compression, compaction, and clones savings. Starting with ONTAP 9.3 offline deduplication and compression scanners start automatically by default and based on a percentage of new data written instead of scheduling.
Data Reduction efficiency is a summary of Volume and Aggregate Efficiencies and Zero-block deduplication: Volume Efficiencies could be enabled/disabled individually and on a volume-by-volume basis: Offline Volume Deduplication, which works on a 4 KB block level Additional efficiency mechanisms were introduced later, such as Offline Volume Compression also known as Post-process (or Background) Compression, there are two types: Post-process secondary compression and Post-process adaptive compression Inline Volume Deduplication and Inline Volume Compression compress some of the data on the fly before it reaches the disks and designed to leave some of the data in the uncompressed form if it is considered by ONTAP to take a long time to process them on the fly, and to leverage other storage efficiency mechanisms for this uncompressed data later. There are two types of Inline Volume Compression: Inline adaptive compression and Inline secondary compression Aggregate Level Storage Efficiencies include: Data Compaction is another mechanism used to compress many data blocks smaller than 4 KB to a single 4 KB block Inline Aggregate-wide data deduplication (IAD) and Post-process aggregate deduplication also known as Cross-Volume Deduplication share common blocks between volumes on an aggregate. IAD can throttle itself when the storage system crosses a certain threshold. The current limit of physical space of a single SSD aggregate is 800 TiB Inline Zero-block Deduplication deduplicate zeroes on the fly before they reach disks Snapshots and FlexClones are also considered efficiency mechanisms. Starting with 9.4 ONTAP by default deduplicate data across the active file system and all the snapshots on the volume, saving from snapshot sharing is a magnitude of the number of snapshots, the more snapshots the more savings will be, therefore snapshot sharing gives more savings on SnapMirror destination systems. Thin Provisioning
Cross-Volume Deduplication storage efficiency features work only for SSD media. Inline and Offline Deduplication mechanisms that leverage databases consist of links of data blocks and checksums, for those data blocks that have been handled by the deduplication process. Each deduplication database is located on each volume and aggregates where deduplication is enabled. All Flash FAS systems do not support Post-process Compression.
Order of Storage Efficiencies execution is as follows:
Inline Zero-Block deduplication Inline Compression: for files that could be compressed to the 8 KB adaptive compression used, for files more than 32 KB secondary compression used Inline Deduplication: Volume first, then Aggregate Inline Adaptive Data Compaction Post-process Compression Post-process Deduplication: Volume first, then Aggregate
Aggregates
One or multiple RAID groups form an "aggregate", and within aggregates ONTAP operating system sets up "flexible volumes" (FlexVol) to store data that users can access. Similar to RAID 0, each aggregate consolidates space from underlying protected RAID groups to provide one logical piece of storage for flexible volumes. Alongside aggregates of NetApp's disks and RAID groups aggregates could consist of LUNs already protected with third-party storage systems with FlexArray, ONTAP Select, or Cloud Volumes ONTAP. Each aggregate could consist of either LUNs or NetApp's RAID groups. An alternative is "traditional volumes" where one or more RAID groups form a single static volume. Flexible volumes offer the advantage that many of them can be created on a single aggregate and resized at any time. Smaller volumes can then share all of the spindles available to the underlying aggregate and with a combination of storage, QoS allows the performance of flexible volumes to be changed on the fly while traditional volumes do not. However, traditional volumes can (theoretically) handle slightly higher I/O throughput than flexible volumes (with the same number of spindles), as they do not have to go through an additional virtualization layer to talk to the underlying disk. Aggregates and traditional volumes can only be expanded, never contracted. The current maximum aggregate physical useful space size is 800 TiB for All-Flash FAS Systems.
7-Mode and earlier
The first form of redundancy added to ONTAP was the ability to organize pairs of NetApp storage systems into a high-availability cluster (HA-Pair); an HA-Pair could scale capacity by adding disk shelves. When the performance maximum was reached with an HA-Pair, there were two ways to proceed: one was to buy another storage system and divide the workload between them, another was to buy a new, more powerful storage system and migrate all workload to it. All the AFF and FAS storage systems were usually able to connect old disk shelves from previous models—this process is called head-swap. Head-swap requires downtime for re-cabling operations and provides access to old data with new controller without system re-configuration. From Data ONTAP 8, each firmware image contains two operating systems, named "Modes": 7-Mode and Cluster-Mode. Both modes could be used on the same FAS platform, one at a time. However, data from each of the modes wasn't compatible with the other, in case of a FAS conversion from one mode to another, or in case of re-cabling disk shelves from 7-Mode to Cluster-Mode and vice versa.
Later, NetApp released the 7-Mode transition Tool (7MTT), which is able to convert data on old disk shelves from 7-Mode to Cluster-Mode. It is named Copy-Free Transition, a process which required downtime. With version 8.3, 7-Mode was removed from the Data ONTAP firmware image.
Clustered ONTAP Clustered ONTAP is a new, more advanced OS, compared to its predecessor Data ONTAP (version 7 and version 8 in 7-Mode), which is able to scale out by adding new HA-pairs to a single namespace cluster with transparent data migration across the entire cluster. In version 8.0, a new aggregate type was introduced, with a size threshold larger than the 16-terabyte (TB) aggregate size threshold that was supported in previous releases of Data ONTAP, also named the 64-bit aggregate.
In version 9.0, nearly all of the features from 7-mode were successfully implemented in ONTAP (Clustered) including SnapLock, while many new features that were not available in 7-Mode were introduced, including features such as FlexGroup, FabricPool, and new capabilities such as fast-provisioning workloads and Flash optimization.
The uniqueness of NetApp's Clustered ONTAP is in the ability to add heterogeneous systems (where all systems in a single cluster do not have to be of the same model or generation) to a single cluster. This provides a single pane of glass for managing all the nodes in a cluster, and non-disruptive operations such as adding new models to a cluster, removing old nodes, online migration of volumes, and LUNs while data is contiguously available to its clients. In version 9.0, NetApp renamed Data ONTAP to ONTAP.
Data protocols ONTAP is considered to be a unified storage system, meaning that it supports both block-level (FC, FCoE, NVMeoF and iSCSI) & file-level (NFS, pNFS, CIFS/SMB) protocols for its clients. SDS versions of ONTAP (ONTAP Select & Cloud Volumes ONTAP) do not support FC, FCoE or NVMeoF protocols due to their software-defined nature.
NFS NFS was the first protocol available in ONTAP. The latest versions of ONTAP 9 support NFSv2, NFSv3, NFSv4 (4.0 and 4.1) and pNFS. Starting with ONTAP 9.5, 4-byte UTF-8 sequences, for characters outside the Basic Multilingual Plane, are supported in names for files and directories.
SMB/CIFS