Enterprise Storage Forum content and product recommendations are editorially independent. We may make money when you click on links to our partners. Learn More.
The days when storage meant how much disk space is on a hard drive may be long gone, but the vast majority of organizations still don’t have dedicated storage specialists. According to a one study, fewer than 25 percent of either Unix-/Linux- or Windows-based IT organizations had their own storage management team at the end of 2004. By the end of 2006, however, that number is expected to soar above 75 percent.
This means that thousands of businesses either have assigned a new guy to storage or are planning to make an appointment in the near future, and it is for them we have prepared this article. Here, we will discuss storage strategies from an entry-level perspective rather than one of super-sophistication found in larger shops with expensive storage-area networks (SANs) already in place.
Definitions Come First
The world of storage can be forbidding to a novice. Even veteran IT personnel may be put off by the sheer volume of new terminology and alphabet soup that has evolved. Before we dive in, let’s sample some basic terms:
Direct Attached Storage (DAS): The server stores data on disks that are in the same box. Redundant Array of Independent Disks (RAID) is used heavily in this approach.
Storage Area Network (SAN): A collection of computers and devices are connected over a high-speed network and are dedicated to the task of storing and protecting data. Instead of storing data locally, each server sends data across the network to a shared pool of storage.
Disk Array: A large array of disks in one box, it is often used as part of a SAN to store data for multiple servers. These servers typically connect to the disk array using Fibre Channel.
Fibre Channel (FC): Optical fiber cables transmit data at high speed in a SAN. Fibre Channel is the transport protocol used for this purpose.
Network-Attached Storage (NAS): NAS separates data from applications by storing data on filers attached to the LAN. Filers can share files across multiple applications, platforms, and operating systems.
Internet Small Computer Systems Interface (ISCSI): This standard enables storage and retrieval at high speed (1 GB/second or higher) over regular IP networks.
This is by no means a complete list of key definitions, but it should make things clearer, or at least be enough to make this article comprehensible.
Basic Strategy — Keep it Simple
Storage is an immense and complex universe. Once you enter, your mind is soon swimming in strange, even alien concepts. Therefore, it is best to stick to what you know and keep it very simple — especially at the start.
One obvious way to avoid complexity is to use the services of a storage service provider. These are firms that lease storage from their own data centers and other services. Colorado Software Architects, for example, offers 1Disk.com. Sun, Arsenal Digital, and Iron Mountain are also among the companies that have recently announced similar services.
The advantage of a storage provider is that the vendor provides a variety of storage options for a fixed cost. This is a handy way to add storage capacity or meet regulatory compliance/archiving requirements without having to build new infrastructure.
|
The basic strategy for storage is to try to stick with the familiar. NAS and iSCSI are good starting points for competent IT departments already familiar with IP networking. FC SANs, on the other hand, should probably be avoided unless you have very large capacity and require the highest possible performance.
|
Of course, simplicity can be taken to extremes (i.e., attempting to pass the entire storage burden to an external source or keeping everything stored on the same old servers using bigger and better disks). Such a strategy eventually runs into a wall; there is so much data stored on so many servers that it becomes impossible to manage.
Beyond DAS, then, where should the rookie storage guy go to ease his woes? Initially, at least, it might be smart to start with NAS and avoid SANs. At its core, a NAS filer is simply a specialized type of server that connects to the network. Storage is rapidly added by plugging the appliance into a network hub or switch. The likelihood is that the server administrator will run into very little that is new to him by buying a NAS box. Lower-end models that are relatively easy to use are available from, Network Appliance , Snap Appliance (now owned by Adaptec), and HP.
The drawback of NAS is that filers and servers share the same LAN. As a result, network performance may eventually be affected. When that juncture is reached, it may be remedied by upgrading the LAN and adding higher-grade NAS equipment. A more long-term solution would be to roll out the first SAN.
Simple SANman Says
Undoubtedly, the land of the SAN can be forbidding. Continuing with our theme of simplicity, the transition to a SAN can be made smoother by beginning with rapidly maturing iSCSI technology. iSCSI allows the establishment of a SAN over an IP network. Thus, the IT department does not need to learn new protocols or add new skill sets to create a SAN. This also has the advantage of being much less-expensive than an FC SAN.
The City of Ogden, Utah, for example, implemented an iSCSI SAN by Left Hand Networks. This proved to be much less expensive than purchasing an FC SAN. The SAN serves about 50 Windows 2000 and Linux servers and three HP HP/UX servers and houses about 1 Terabyte (TB)
“Ogden’s data storage requirements are expected to grow in the next few years into six to 10 TB,” says Jay Brummett, CTO of the City of Ogden.
The SAN is physically isolated from Ogden’s existing production LAN/WAN. The physical separation ensures SAN performance and security are not adversely affected or mingled with standard LAN/WAN traffic.
“The whole process from start to finish required less than four hours from the time we broke the tape on the cartons until the drives were online and ready to be loaded with data,” said Brummett “Calculated cost per megabyte has dropped from $0.62 to $0.18 without factoring in the reduced cost of management or the leveraging of existing Ethernet know-how.”
Other IP SAN offerings include, MPC Corp’s (formerly Micron PC) DataFRAME series, Dell’s AX100, and StoneFly Networks’ products.
Super-Size It
iSCSI is especially appropriate for companies with IP backbones capable of handling gigabit traffic. While the technology is improving rapidly, it doesn’t offer the same speed or capacities as a heavy-duty FC SAN. Similarly, SANs offer higher speeds and throughput than NAS systems. To do this, they offload data traffic to a separate network for storage devices.
On the negative side of the ledger, however, SANs may have difficulty supporting multiple operating systems and platforms. In addition, some users complain about being unable to integrate SAN solutions from different vendors.
Who needs an FC SAN? The NASA Advanced Supercomputing (NAS) facility at Ames Research Center in Mountain View, Calif. is one organization that did. The facility houses a new 450 TB storage network working in tandem with the massive Columbia supercomputer, which runs on Intel Itanium 2 and Linux. Everything exists within one massive InfiniteStorage SAN from SGI. Result: Simulations of a decade’s worth of changes in ocean temperatures and sea levels that used to take a year to model can now be created in a day or two. Further, instead of scientists queuing up for supercomputing resources, there is now enough capacity for everybody.
“All of the storage is within one big SAN,” said Bob Ciotti, Terascale Systems Lead at NASA. “We now have 200 TB of data on Fibre Channel and 250 TB on Serial ATA arrays (SATA).”
SANs don’t have to be that big to be valuable or affordable, but they are made up of highly specialized components that require strong internal expertise.
Other vendors offering SAN-based products and services include: EMC, Brocade, and Hitachi Data Systems.
Choose Wisely
The basic strategy for storage is to try to stick with the familiar. NAS and iSCSI are good starting points for competent IT departments already familiar with IP networking. FC SANs, on the other hand, should probably be avoided unless you have very large capacity and require the highest possible performance.
If so, it is best to recruit a dedicated storage team to wrestle this beast and bend it to your corporate will. Although the cost and complexity are greater in the short term, the potential long-range payoff is greater than with NAS or iSCSI.
And for those that just don’t want to involve themselves in yet another IT skill set, managed storage services now cover the entire spectrum. Sometimes it is just less-expensive, easier, or faster to call in the professionals and leave everything to them.
For More Information
For a more rounded look at storage basics, we recommend:
- Storage Area Networks for Dummies by Christopher Poelker (published by Wiley)
- Storage Networks Explained by Ulf Troppens (published by Wiley)
- Using SANs and NAS by W. Curtis Preston (published by O’Reilly)
- Association of Storage Networking Professionals (an end-user organization with more than 2,000 members that offers plenty of advice, papers, meetings, and discussion forums to help those finding their way in storage.
