10 GbE: iSCSI bandwidth increase improves protocol’s position against FC

With a boost to iSCSI bandwidth with 10 Gigabit Ethernet, products that support the protocol offer features to rival Fibre Channel SANs, including scalability and hypervisor integration.

With the advent of 10 Gigabit Ethernet, iSCSI is now a more viable protocol than ever for connecting pools of storage to large virtual server and desktop environments.

Where previously administrators tended to favour Fibre Channel due to concerns over iSCSI bandwidth, connectivity, availability and contention rates, 10 GbE iSCSI can now step up to the plate.

With the increase in bandwidth to 10 GbE, an iSCSI network can provide a common infrastructure for storage and LAN traffic with capacity that matches that commonly available with Fibre Channel.

And, iSCSI allows the option of software- or hardware-based approaches to implementation and management of storage in the virtual environment.

A dedicated hardware approach would, for example, use 10 GbE iSCSI NICs and segregate traffic with a VLAN implementation, effectively creating a 10 GbE IP fabric with individual VLANs mimicking Fibre Channel zones.

Or, in a software-based approach, iSCSI can slot into an existing 10 GbE network environment with connections directly to storage from virtual hosts via software initiators.

No matter whether a software- or hardware-based approach is used, the keys to efficiency in whatever implementation selected to take advantage of greater iSCSI bandwidth are solid IP fundamentals with proper attention to traffic contention, host device capability and consistent ongoing IP environment monitoring. Now, let’s review the range of products in this space.

iSCSI for the SME/branch office market

Many storage array vendors now offer SAN systems with 10 GbE connectivity. Many can be used with file- or block-based access methods and are designed to be interoperable with virtual environments. Ethernet connectivity is provided by on-board interfaces, which are either integrated or enabled through the use of 10 GbE small form-factor pluggable (SFP) transceivers.

Dell. Dell’s PowerVault MD3600i/MD3620i modular arrays provide controllers with two native 10 GbE iSCSI ports that do not require SFP transceivers. SSD, SATA and SAS drive support is included with a maximum 96 drives per array through the addition of extra trays, and single- or dual-controller configurations are available with tiered implementation across multiple connected modules.

Dell’s EqualLogic brand offers the PS4110E 10 GbE iSCSI array, which supports one integrated standard 10 GbE interface plus an additional SFP-based 10 GbE connection. With a maximum number of concurrent storage volumes of 256 and support for up to 512 concurrent access hosts, the PS4110E can also be combined into a storage group with another unit providing data centre bridging services.

Nexsan. The Nexsan NST5000 series is another IP SAN product that offers stacking capabilities and two 10 GbE interfaces per controller. The flagship NST5500 features VMware, Citrix XenServer and Microsoft Hyper-V compatibility and a maximum capacity of 1 petabyte (PB) of raw storage with the addition of an expansion chassis allowing for 360 SATA or SAS drives. Thin provisioning and data tiering are also supported for virtual environments across the range.

Stonefly. A lesser-known brand, Stonefly, produces the Integrated Storage Concentrator product family of IP-based SAN arrays, which are certified for use with VMware, Xen, Hyper-V and Linux KVM virtual environments and offer up to eight 10 GbE iSCSI ports. Thin provisioning is standard across the range and SAS/SATA/SSD disk support is provided, with the ISC3604-6GS flagship unit supporting 216 total drives (the base configuration is 36 drives, which can be expanded by an additional 180 drives split among three trays). Tiered storage, iSCSI port teaming (in which two or more Ethernet ports are combined together) and load balancing are also available on the Stonefly storage range.

iSCSI for the enterprise

iSCSI in the past has been regarded as almost a “budget” option for storage connectivity, but the focus is now shifting; increasing bandwidth availability is making connectivity options with 10 GbE an important component of a multiprotocol capability for larger enterprise environments. As such, 10 GbE iSCSI is now an option on multiprotocol storage arrays from all the main players in this market.

NetApp. The FAS3000 and the FAS6000 platforms from NetApp offer 10 GbE as an option for block- and file-based connections to the same device. The FAS3070 offers 504 TB of raw storage with Fibre Channel or SATA disk capability and a maximum of 32 10 GbE ports. The FAS6080 offers 1,176 TB of raw storage with a maximum of 52 10 GbE ports. In addition, NetApp controllers now feature Unified Connect, which offers concurrent support for FCoE and IP storage traffic over shared 10 GbE connections.

IBM. The DS5000 series from IBM offers 10 GbE iSCSI connectivity with support for all drive types, including SSD. The top-of-the-range DS5300 supports a maximum of 480 drives with 64 GB of cache in a dual-controller configuration and offers eight 10 GbE iSCSI host ports.

EMC. The newest member of the Symmetrix series from EMC, the VMAXe storage system has a maximum cache of 512 GB with support for SSD, SAS and SATA drives. It offers a maximum of 32 10 GbE iSCSI ports per array and total raw space of 1,490 TB at RAID 5 along with multiprotocol connections via optional additional interfaces.

Also from EMC, the VNX SAN series offers both block and file access across the range. The high-end VNX7500 can hold eight 10 GbE Ethernet ports per X-Blade controller, which are stackable up to a maximum of eight, giving 64 potentially available 10 GbE ports per array.

Hitachi Data Systems. Hitachi’s Adaptable Modular Storage Model 2100, 2300 and 2500 controllers all offer four onboard 10 GbE ports, as do all the controllers in the Hitachi Unified Storage 100 product range. An interesting feature of the Storage 100 range is its capability to combine block, file and object-oriented storage types under a single platform. And, finally, the Hitachi Unified Storage 150 model is the Rolls Royce option of the series, offering SAS and SSD support with a maximum raw space capacity of nearly 3 PB across 40 expanded arrays, with dual controllers, thin provisioning and auto tiering also included.  

Martin Taylor is converged network manager at the Royal Horticultural Society.


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