IP Storage - Where does it fit and what does it mean?
Building a storage infrastructure.
By Hamish Macarthur | Published: 08:00, 23 September 2004
The new developments in IP storage are of great interest to users who are looking to harness their existing investments in IP networks, both local and across their organisation. With an increasing spread of storage devices, directly connected and otherwise, a key consideration is to develop a secure network infrastructure cost-effectively. Using existing capacity on LANs is one attractive approach.
This is where networked attached storage (NAS) comes in. It will deliver support of databases and files to applications running on the servers connected to the network. Within the NAS device, there are several key features that will enable sound storage management. These include the mandatory implementation of RAID levels and volume management to support the structuring of the disk array and Snapshot for just-in-time copies. In addition, options such as tape attachment will enable backups to be made from the NAS device, employing the NDMP protocol, specifically developed for the purpose, and taking traffic away from the network.
But the focus for data protection is now on using the disk-based NAS devices themselves instead of tape drives or libraries. There has been an ongoing practice of using additional high-cost disk devices for immediate mirroring of datasets. With the availability of serial ATA (SATA) drives, more cost-effective options are available. These new NAS devices are implemented in the legacy networks and the only change in the existing ‘backup and restore’ processes is the device to which the backup is written to.
So one area where IP storage fits is the consolidation of disk storage on the existing IP LAN, using the existing network infrastructure and in some cases the established data protection practices, now focused on disk. Suppliers for these solutions include EMC and Network Appliance through to HP with its mid range NAS offerings, and companies such as Quantum and Overland with their SATA devices targeted at smaller networks.
Linking into SANs
The view that you either have a NAS or SAN-based infrastructure is outmoded. The reality is that both can coexist as they offer complementary services. How does the IP storage paradigm fit in with a SAN? The underlying need is usually when the data on the LAN can be protected and managed on an established SAN, yet the primary need is for file-based applications to be supported, with minimal change to the operations of these applications.
What is effectively the controller element of the NAS arrays discussed above can operate as devices connecting LANs to SANs – these are often referred to as NAS heads. The disk arrays on the SAN now become the devices that store the data. Applications can now be directed to reading the data from a different drive, accessed across the LAN, while physically the data is located on the SAN. Suppliers offering such devices include EMC and Network Appliance.
What about supporting the ubiquitous Exchange servers?
Microsoft has taken a view that Exchange requires a special type of support. This has meant that NAS devices have not been fully supported with Exchange unless Windows Storage Server is implemented. With Windows Storage Server embedded into new NAS devices targeted at the mid-range and smaller networks, this now takes away a major hurdle faced by users in consolidating their storage resources across their LANs.
And IP SANs
Implementing new protocols is always a challenge for vendors and users alike. iSCSI is no exception. With much talk over the last few years, the ramp-up for this protocol is not too far away. Standards are now finalised and testing of options is taking place in the vendors’ labs. The great benefit of such a technology is that users can leverage their existing switches and networks.
Connectivity to such SANs is now available either through accelerators such as TCP Offload Engines (TOEs) or, if connected through a server, Microsoft iSCSI drivers are available free of charge on the Web. The complete iSCSI infrastructure, with the resilience and support that is exhibited by Fibre Channel, is now shaping out; switch suppliers such as McDATA, Cisco, CNT and Brocade are offering such support. Qlogic has also entered this market and is positioning to offer the support for IP SANs, especially for new users looking to extend their current investments.
Where IP Storage fits
In the overall picture, IP storage is a natural development which enables users to build sound infrastructures to support their information management needs. Harnessing the existing investment in IP networks, the options for networked storage have just become richer. Storage can now be consolidated across the LAN, linking LANs and SANs and support most all applications. Finally, let us not forget that there is also the need to link remote sites together. Again across the IP networks, these options have also been addressed in an earlier article in this series titled Multiprotocol routing - supporting a changing world.