Western Digital (formerly Tegile) storage systems provide multi-protocol storage with either hybrid storage using spinning media and NAND flash solid-state or all flash storage. Offerings include SAS attached flash storage devices or PCIe attached flash with NVMe protocol.
The system design leverages common hardware platforms with the most recent models utilizing standard bridge-bay controllers and storage in a single 2U enclosure. Storage controller features are delivered through a combination of open source ZFS, combined with Western Digital developed features, CLI and GUI.
Flash is used to enhance the performance of the log-structured filesystem at the core of Western Digital systems. Use of Flash accelerates write performance by allowing the system to acknowledge a write and then coalesce data before storing it across solid-state drive modules. Recently accessed data is stored in a separate Flash read cache, enhancing read performance.
Western Digital’s systems are multi-protocol storage designed for use in general purpose environments with high performance requirements, or multiple workloads running on the same storage system. The multi-protocol file and block access provides both application and host connectivity options, which are particularly well suited to deployments where flexibility is an advantage.
All current Western Digital models are dual controller systems for high availability and include data protection features. The Western Digital architecture includes multiple RAID levels, including dual (RAID 6) and triple parity RAID, along with two-way mirroring (RAID 1) and three way mirrors. Space efficient snapshots are included with the system, which supports a nearly unlimited number of both read only and read-write snapshots. Additionally, remote asynchronous replication over iSCSI is available.
Incoming data is written to flash acting as NVRAM and mirrored to the partner controller in HA configurations. Next, a write acknowledgement is sent to the client. In-line data deduplication and compression are available, using unique hashes as a first check and then a byte-wise comparison for final validation of data duplication. The tracking of duplicate blocks of data is handled by the MASS storage controller, which also performs compression. Data may be pinned to SSD for high performance volumes dedicated to specific applications.
In 2017 Western Digital announced new models that support dual-ported PCIe attached SSDs that utilize NVMe protocol. Different endurance level SSDs are available for different usages at different price points. In 2019 Western Digital expanded their line of NVMe capable products with the more affordable N5100 model. Western Digital also uses the internal tiering software to support different classes of flash devices.
The IntelliFlash OS 3.10 announcement added new software features such as Live Dataset Migration to migrate data pools to other IntelliFlash systems and Hybrid Cloud Connector to send snapshots to S3 supported clouds.
Western Digital systems are designed as general purpose, high performance storage systems competing with other midrange storage systems. Target applications are those requiring high performance, particularly those with large capacity requirement. Effective capacity with compression and deduplication is listed as 4X the raw capacity.
Current generation systems are highly available (HA), providing all hot-swap components with active / active controllers with symmetric LUN access. This enables non-disruptive access during component failures and upgrades, including for host access paths or storage controllers.
The controller firmware supports FCP and iSCSI block access, along with CIFS and NFS file access via the HA controller nodes. Western Digital has announced that NVMe over Fabric will be delivered in the future.
IntelliFlash software offers support for VMware Web client and vCenter plugins. The VMware support enables users to perform storage allocation along with performance and capacity management from within the VMware console. Additionally, support for VMware VAAI provides enhanced performance with VMware based workloads, including thin reclamation, block zeroing, and virtual machine cloning operations.
The ability to pin data into flash SSDs may further enhance performance. Specific volumes or filesystem mount points for NFS may be designated as residing in flash. When pinned, data must be copied onto the SSD cache but will remain in the cache until the system is restarted.
While there is asynchronous replication, there is no VMware SRA plugin, reducing the DR capabilities of Western Digital.
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Western Digital added management software and created multiple, dual-controller models to deliver an all-flash or hybrid system with low entry prices. The maturity of the ZFS NAS implementation includes a full spectrum of file protocols, more than is usual in most products. A full suite of advanced features is also available including migration of snapshots to S3 compatible clouds and object storage.
The IntelliFlash is not a scale-out system, which means for increasing performance in parallel with capacity, a new controller pair (another model) must be installed. Other competitive systems have implemented scale-out functionality for a more measured growth. Evaluator Group believes that at some point Western Digital will add scale-out capabilities to the system as a competitive necessity.
Western Digital has done well with tuning the system for block performance and addressing needed characteristics for an all-flash storage system in enterprises.