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IS THE SUN GOING DOWN ON NAS?

From STORAGE Magazine Vol 9, Issue 6- September 2009

NAS (NETWORK ATTACHED STORAGE) HAS BEEN A GREAT SERVANT TO THE INDUSTRY, BUT HAS IT HAD ITS DAY? ARE OTHER KEY TECHNOLOGIES NOW SUPPLANTING IT? BRIAN WALL FINDS OUT

There are some pundits and commentators who are saying that NAS - network attached storage - has had its day; run its course. That, yes, it pioneered so much that is good about storage, but should now be put out to pasture and allowed to retire gracefully. If that is the case, then who might the pretenders to its crown be - storage area networks (SAN), for example - and what superior benefits do those technologies have to offer? On the other hand, is NAS being written off too soon in some quarters, and so still has a significant role to play as new generations of NAS products evolve and mature? NAS has indeed been a great servant to the industry. It has been used to great effect to provide a way to consolidate CIFS and NFS protocols into a single storage solution. The world of NAS, however, has evolved dramatically and the explosion of data has been unrelenting. According to EMC's IP experts, consumers demand more flexible, easier to use, scalable solutions that offer automated tiering of storage to provide a range of costing options throughout the lifecycle of data. "Customers now require protocol flexibility, providing storage for use with Windows file shares, UNIX file shares and block-based storage (iSCSI and fibre channel)."

That's right! NAS, they insist, has evolved from supporting only file-based protocols and is now unified storage, which "provides all the protocols that the storage architect will need to meet their ever changing storage infrastructures". Moreover, this evolution of protocol connectivity is set to continue with greater convergence of network protocols, driven by the expected adoption of FCoE (fibre channel over ethernet).

PROVING GROUND

Historically, the NAS platforms have been the proving ground for new technologies, including point in time copies of data, virtual provisioning, iSCSI and primary storage de-duplication. User demand has been to converge these technologies into the traditional FC SAN environments delivering innovation and flexibility, while maintaining an appropriate price point for the market.

"Storage is just one component of the modern information infrastructure solution," EMC's experts told Storage magazine. "Unified storage offerings provide the perfect basis for application consolidation (including Exchange, SQL, Oracle, Sharepoint) in both the physical and virtual server infrastructure. One of next logical components, alongside disaster recovery and archive of data, in the solution is obviously fast, efficient backup of data within the environment." And hey, presto,

you have laid the foundation for progressively moving towards full virtualisation and a fully fledged cloud environment.

According to Ian Booth, IT manager at Ainscough Cranes, this is very much the way forward. "Thanks to VMware, EMC and STACK, we are now confident that our data is secure," he says, "because we know where it is at all times, and can rest assured now that it is backed up and offsite. This is underlined by the fact that we now maintain a 99.999 percent uptime."

The choice of the NS20 enabled the company to connect to multiple storage networks via network-attached storage (NAS), iSCSI, and a fibre channel storage area network (SAN). This eliminated the problems of stranded file servers and applications, and helped scale capacity, without compromising performance. The one terabyte (TB) SATA drives in the NS20 also helped boost energy efficiency.

NAS STRENGTHS

So what has made NAS such a winner? Well, it challenges the traditional file server approach by creating systems designed specifically for data storage. Instead of starting with a general-purpose computer and configuring or removing features from that base, NAS designs begin with the bare-bones components necessary to support file transfers and add features 'from the bottom up'.

Like traditional file servers, NAS follows a client/server design. A single hardware device, often called the NAS box or head, acts as the interface between the NAS and network clients. These NAS devices require no monitor, keyboard or mouse. They generally run an embedded operating system, rather than a full-featured NOS. One or more disk (and possibly tape) drives can be attached to many NAS systems to increase total capacity. Clients always connect to the NAS head, however, rather than to the individual storage devices.

Clients generally access a NAS over an ethernet connection. The NAS appears on the network as a single 'node' that is the IP address of the head device. A NAS can store any data that appears in the form of files, such as email boxes, web content, remote system backups, etc. Overall, the uses of a NAS parallel those of traditional file servers. NAS systems strive for reliable operation and easy administration. They often include built-in features, such as disk space quotas, secure authentication or the automatic sending of email alerts, should an error be detected.

NAS PROTOCOLS

Communication with a NAS head occurs over TCP/IP. More specifically, clients utilise any of several higher-level protocols (application, or layer seven protocols in the OSI model) built on top of TCP/IP. The two application protocols most commonly associated with NAS are Sun Network File System (NFS) and Common Internet File System (CIFS). Both NFS and CIFS operate in client/server fashion and predate the modern NAS by many years; original work on these protocols took place back in the 1980s. NFS was developed originally for sharing files between UNIX systems across a LAN. Support for NFS soon expanded to include non-UNIX systems; however, most NFS clients today are computers running some flavour of the UNIX operating system.

The CIFS was formerly known as server message block (SMB). SMB was developed by IBM and Microsoft to support file sharing in DOS. As the protocol became widely used in Windows, the name changed to CIFS. This same protocol appears today in UNIX systems as part of the Samba package. Many NAS systems also support hypertext transfer protocol (HTTP). Clients can often download files in their web browsers from a NAS that supports HTTP. NAS systems also commonly employ HTTP as an access protocol for web-based administrative user interfaces.

LESS COMPLEX

NAS products improve on traditional file servers generally through the principle of simplification. By stripping out all of the unnecessary capabilities of a general- purpose server - applications, services or daemons, and hardware peripherals - a NAS device becomes less prone to system crashes and security attacks. Moreover, when a problem does occur, a NAS system can be diagnosed and rebooted much faster, due to its lower level of complexity.

NAS products also generally hide the operating system personality of the device. Whereas Windows, UNIX and NetWare file servers each demand specific protocol support on the client side, NAS systems strive for greater operating system independence of clients.

THE OPPOSITION

Opponents of NAS emphasise that traditional file servers have a proven record of success, compared to this new breed of 'upstart' NAS systems. High-end file systems also contain more processing power than a NAS device, giving servers a performance edge (in terms of transactions or I/O per second rates) over NAS.

At a high level, SANs serve the same purpose as a NAS system. A SAN supplies data storage capability to other network devices. Traditional SANs differed from traditional NAS in several ways. Specifically, SANs often utilised fibre channel, rather than ethernet, and a SAN often incorporated multiple network devices or 'endpoints' on a self-contained or 'private' LAN, whereas NAS relied on individual devices connected directly to the existing public LAN. The traditional NAS system is a simpler network storage solution, effectively a subset of a full SAN implementation.

The distinction between NAS and SAN has grown fuzzy in recent times, as technology companies continue to invent and market new network storage products. Today's SANs sometimes use ethernet, NAS systems sometimes use fibre channel, and NAS systems sometimes incorporate private networks with multiple endpoints. The primary differentiator between NAS and SAN products now boils down to the choice of network protocol. SAN systems transfer data over the network in the form of disk blocks (mentioned earlier - fixed- sized file chunks, using low-level storage protocols, such as SCSI), whereas NAS systems operate at a higher level with the file itself.

Undoubtedly, the new breed of NAS networking products has succeeded in providing a compelling alternative to traditional file servers in client/server networks. Moreover, entry-level NAS products containing 20-50 gigabytes of storage can be purchased at quite reasonable prices, whereas mid-range and high-end NAS systems can run into several thousands of pounds. Besides cost, a NAS promises reliable operation and easy management. So, rather than expecting the demise of network attached storage technology any time soon, the likelihood is that it will continue to keep evolving as the field matures.