Unified storage has come to mean the delivery of block and file storage from within a single platform. The initial incarnation of these devices consisted of a block storage array with the addition of a file gateway, enabling both file and block protocols to be supported in a single configuration.
Today, that’s still an approach that’s common among storage vendors, and the only major vendor to offer a truly integrated unified platform is NetApp. Its FAS series of devices don’t require the addition of separate hardware to provide for file or block. Most other vendors have avoided this route, either by design or because it has been easier to retain separate components following acquisitions.
But, having a single piece of hardware from which any protocol can be enabled through software does have its benefits, in terms of cost and flexibility. However, unless unified technology can manage the different workload profiles of file and block (and, crucially, at the same time), performance problems could be encountered.
Over the last 12 months or so, we have seen the major storage vendors delivering or enhancing unified storage products that offer the range of typical file and block protocol support, including iSCSI, Fibre Channel, CIFS/SMB and NFS. Fibre Channel over Ethernet (FCoE) support is also available from NetApp and EMC.
In some cases these unified storage products are truly integrated, both physically and at the software level. Many solutions on offer are hybrid devices that follow the path of adding a file gateway to a block storage product. Through acquisition, Dell and IBM have added file protocol technologies to existing platforms. Although they are hybrid by nature of being a mixture of file and block hardware, they are being packaged as unified (and therefore fully supported) solutions.
EMC replaced its separate Clariion and Celerra products in early 2011 with a single product line that combined both former products into one platform, the VNX. Meanwhile, HP has partnered with Microsoft to use the Windows Storage Server (WSS) as the basis for its gateway products.
Feature support among the vendors[CE1] is extensive, with typical options including thin provisioning, policy-based file management and, increasingly, data deduplication. Solid-state drives (SSDs) are available from most vendors and can be exploited fully using thin provisioning and automated storage tiering technology.
Finally, we should mention that there are a number of newcomers to the unified storage marketplace, including startups Starboard Storage Systems and Tegile Systems. Both companies have developed technology that specifically targets the I/O profile of a mixed file and block workload. These devices are easier to deliver today because of the advances in processor speeds and integration of I/O protocols further into processor chipsets. Over time, we will likely see more of these solutions emerge that truly bring multiprotocol together in a single device. Now let’s examine the major vendors’ updates to their unified storage lines over the past year.
Early in 2011 EMC announced its unified platform, the VNX, as a replacement for the previous Clariion and Celerra product lines. This converged product family combines block and file protocols in a single platform, managed by the new Unisphere management software.
VNX hardware combines file and block protocols (delivered in separate enclosures), providing file I/O using X-Blades -- hardware blades that were known as data movers in the previous Celerra solution. The VNX models start at the entry-level VNX 5300, which supports a maximum of 125 drives; up to the VNX7500, which supports 1,000 drives, including flash, SAS and nearline SAS devices. Protocol support includes NFS, CIFS, MPFS, pNFS, FC, iSCSI and FCoE.
There is a range of additional functionality available with the VNX, including Fully Automated Storage Tiering for Virtual Pools (FAST VP) auto-tiering technology, Fast Cache (enhanced cache performance for random I/O workloads), data compression and thin provisioning.
EMC also offers the VNXe, which is aimed at small businesses. VNXe combines block and file support into a single unit, scaling to a maximum of 120 drives on the VNXe3300 model. Although the VNXe is targeted at SMBs, the device does still provide compression and thin provisioning technologies.
The VNX range has been upgraded over the last 12 months with faster processors and additional memory. SAS drives are now the standard disk connection.
NetApp FAS devices were one of the first unified storage devices on the market, supporting file and block protocols in a single platform. As discussed earlier, the company’s technology was also unique in that it supported the protocol range within a single hardware device, rather than using block storage with a NAS gateway. In September 2011, NetApp upgraded its FAS2000 series with the release of the FAS2240. This provides support for up to 8 Gbps Fibre Channel and 10 Gbps Ethernet IP connectivity, covering NFS, CIFS and iSCSI protocols. The higher-end FAS arrays now support FCoE.
NetApp unified solutions are only available with Data Ontap 8 7-mode, which retains backward compatibility with previous platforms. This limits the size of file shares to 100 TB. Scalable NAS is available using Data Ontap 8 Cluster Mode, but this doesn’t provide unified capabilities.
Hewlett-Packard has a range of unified devices across its portfolio. The new X3000 series is based on Microsoft WSS 2008 R2 and runs on standard ProLiant hardware. Microsoft’s WSS platform has a number of additional features, including single-instance storage (SIS); file deduplication technology; and file classification, which delivers policy-based management of files. The X3000 range provides only minimal internal storage and can be connected to external HP arrays including P4000, EVA and XP but is not as truly integrated as solutions from other vendors.
The HP P4000 G2 Unified NAS Gateway offers similar functionality to the X3000 series in that it uses WSS 2008 R2 as a gateway to the LeftHand P4000 G2 array. The NAS gateway has no usable storage of its own and so has to be deployed in conjunction with the P4000 platform.
In 2010 IBM announced the Storwize V7000, a new storage platform based on its SVC storage virtualisation technology. The V7000 was enhanced in October 2011 to provide file and block protocols through the addition of a separate file module, built on IBM’s existing Scale Out Network Attached Storage (SONAS) technology. The V7000 offers a range of additional functionality, including support for SSD and thin provisioning. Data tiering is implemented with IBM’s Easy Tiering feature. The IBM Active Cloud Engine technology implements policy-based file management, automating the movement of less frequently accessed data to lower tiers of storage and, where required, the deletion of files.
The Storwize V7000 supports Fibre Channel up to 8 Gbps, 1 Gbps and 10 Gbps Ethernet for iSCSI and NAS and a maximum of 240 drives, expandable in 12- or 24-drive bay enclosures for a total capacity of 720 TB in a clustered configuration.
In 2010 Dell acquired the assets of Exanet, which provided it with access to clustered NAS technology. This technology was released in June 2011 as the Dell EqualLogic FS7500 Scale-out Unified Storage. This combines EqualLogic storage and the ExaStore file system, rebranded as the Dell Fluid File System. The FS7500 supports iSCSI, CIFS and NFS protocols and is scalable to a maximum system size of 509 TB, with no restriction on the size of a single file share.