Storage has made its way from the bottom of the IT to-do list to become one of the most critical challenges facing the enterprise today. With the development of networked storage and the ever-increasing amounts of digital information, direct-attached storage methods just aren’t cutting it. The debate concerning storage area networks vs. network attached storage has many an enterprise confused about what the right solution is to suit their needs. To make matters worse, the lines between the SAN and NAS worlds are shifting into a blurred mess and products that combine the functionality of both are appearing on the hazy horizon. So what is an enterprise to do? Believe it or not, the answer is not as difficult as it may appear.
The Demise of DAS
Although industry analysts have varying opinions on the most suitable storage solutions for the enterprise, one area they unanimously agree upon is that direct attached storage (DAS) is on its way out, being replaced by the faster, more scalable networked storage technology.
According to IDC Canada’s Alan Freedman, research manager, infrastructure and hardware in Toronto, DAS still makes up approximately 80 per cent of the storage market in Canada. However, he noted that growth rates are really taking off for networked storage.
“We are predicting that by the end of 2002, it should be about half and half – networked storage revenues vs. direct attached storage revenues,” Freedman said. “Networked storage is going to be a hot market this year at the expense of DAS.”
Illuminata’s John Webster agreed with Freedman’s assessment. Webster, senior analyst with the Nashua, N.H.-based research firm, said DAS is slowly being phased out in favour of networked storage, but Webster added that he doesn’t anticipate the demise of DAS this year. Instead he predicts it will happen a little further down the road.
Such is the opinion of Arun Taneja, a senior analyst with Milford, Mass.-based Enterprise Storage Group.
“DAS has serious issues in terms of scalability and availability,” Taneja said. “If a server goes down in a DAS environment, all the storage that was available behind it was unavailable, period.”
This, Taneja noted, is unacceptable from today’s standards and added that with the option of networked storage, “no one in their right mind today should be implementing DAS.”
What, then should the enterprise be implementing? Enter the SAN vs. NAS debate, an area where neither vendor nor analyst can agree.
Files or Blocks or Both? Oh My!
In order to determine the best networked storage solution for your business, you must first take a look at the options: SAN and NAS.
Illuminata’s Webster said that for enterprises that have no qualms in learning Fibre Channel and who need to share resources, a storage area network is likely in the cards. However, he noted that the SAN has not gained as much market share as many SAN vendors had hoped.
“SANs have made a lot of noise but haven’t made a lot of penetration,” Webster said. “That is because they are complex. In a lot of cases, people cannot afford a new storage project, which is what installing a SAN often ends up being.”
On the flip side, he said that network attached storage is the dark horse in the storage race. NAS is IP-based and is much simpler than SAN deployments, Webster said.
“Growth in NAS is really gathering a lot of momentum faster than SAN,” he explained. “The enterprise customer can take a NAS appliance and simply plug it into the network.”
However, according to Storage Analyst Dan Tanner with the Boston-based Aberdeen Group, determining the right storage solution for the enterprise starts with the basics: realizing the needs of the enterprise.
NAS and SAN do exactly different things, he said. What SAN does well, NAS does poorly and vice versa.
“NAS is file space,” he explained. “NAS is just DAS attached to a special server called a filer. You can’t share the storage that belongs to that server and you can’t easily do back-ups because you’ll tie up the LAN.”
He said that on the other hand, SANs are basically multiple DAS devices made up into one large device that have no knowledge of files. SANs are good for sharing volumes and doing back-ups, he said.
When thinking of NAS and SAN solutions and which one best suits your needs, Enterprise Storage Group’s Taneja offered this easy method: the IT manager must decide whether the applications are file-oriented or block-oriented. Although he admitted that not a single enterprise in the world can only deal with one or the other, his advice to the enterprise is to start with the fundamentals.
“Most enterprises are going to have a need for both SAN and NAS solutions,” Taneja said. “Don’t get hung up on SAN or NAS and which is better or less expensive. Start with what your application is. If it is file-oriented, you need NAS; if it is block-oriented you will need SAN. The worlds of SAN and NAS are becoming muddier than they used to be, but start with the simple stuff first.”
Muddy Water
The lines between SAN and NAS are indeed blurring, said Jeff Goldstein, CEO of Network Appliance Canada in Toronto. According to Goldstein, what is driving customers is the need to reduce costs associated with data management, back-up and recovery.
“NAS is a very cost-effective way to manage storage,” Goldstein said. “But the argument is that NAS cannot be used for database because it is too slow.”
This is an argument that neither Goldstein nor Illuminata’s Webster agree with. According to Webster, NAS has debunked its “too slow for database” stigma and has proven itself a worthy candidate to run such applications, which was believed could only be done with SAN devices.
One user decided to test the theory. Going on the success it had in the past with Network Appliance NAS solutions, York University in Toronto opted to use Net App filers to support Oracle-based applications and found it to handle the database extremely well.
“The NAS storage for us was a lot less expensive than going with a SAN,” said Marshall Linfoot, manager of Unix technical support, computing and network services for York University. “It is much easier for us to do our back-up now because it is backing up right off the Net App filer to a tape device, where before with multiple machines and multiple copies of data, we were doing multiple back-ups across our network.”
According to Goldstein, Network Appliance is working toward extending the capabilities of NAS solutions. The company is helping in the development of iSCSI, a new standard that is capable of doing block-mode over IP. The new iSCSI standard would enable NAS solutions to be able to do both file serving and block serving, however it is still currently in development. The company is also in the process of co-developing another storage standard called direct access file systems (DAFS).
“What it does in a database is let the server talk to the storage between the server memory and the storage memory,” Goldstein said. “It is memory-to-memory access instead of memory-to-disk access. It is a lot faster and will give you a new way to attach servers to your storage.”
Although he somewhat agreed that the lines between SAN and NAS are not as distinct as they were last year, EMC’s Ken Steinhardt, director of technology analysis in Hopkinton, Mass. said that what has been significant is that the blurring has been in masking the interface and requests as far as users and customers are concerned.
“We have had the ability at EMC for a while to let a request come in from the network to let a user get information without having to go to a different SAN or NAS device,” Steinhardt said.
He added that EMC has already merged the two storage methods to some extent, such as with its CLARiion product, which is designed to be able to be either a SAN device or a NAS device and can switch from one to another.
Data overflow
As far as Liz Reid is concerned, EMC’s SAN storage solutions were the answer to her growing storage concerns. Reid, vice-president of IT services delivery centre for New Horizon System Solutions (NHSS), said that when the Ontario government deregulated the electricity market to allow competition, Ontario Power Generation (OPG) was forced to lease the Bruce Nuclear Power Plant to Bruce Power. The change in plant control caused the split of all IT systems in order to provide Bruce power with services required to support a standalone enterprise.
NHSS was brought in to find a reliable and scalable disaster recovery infrastructure for the two major clients. According to Reid, the plan was to create one primary site for each customer with each site acting as the disaster recover site for the other. In March 2001, Reid said NHSS opted for EMC’s Symmetrix Remote Data Facility software and split OPG’s environment into two mirrored sites.
“We provide over 30TB of storage for our customers, “Reid said. “The migration alone that we did last year for Bruce Power (and OPG) was 1.5TB and took us only six hours to migrate. Using EMC technology we are able to, over two data centres, provide back-up and recovery facilities for our clients in a much tighter time frame.”
Reid said had NHSS used traditional tape back-up methods, the migration could have taken up to three days to complete.
NHSS has continued to rely on EMC SAN products in its data facilities, Reid said.
“It is a very robust infrastructure that is able to support multiple platforms and is very scalable,” she said.
In the meantime…
While the role of tape has not vanished quite yet to the wings within the enterprise, the role of networked storage has definitely taken centre stage.
Enterprise Storage Group’s Taneja predicted that the world will collapse SAN/NAS functionality in single boxes. However the enterprise should not expect these solutions from the big guys like Compaq, HP, EMC or Net App just yet. He said that it is the small start-ups that are currently developing these dual-functionality boxes and will likely drive the big players to look to do so as well.
However, Illuminata’s Webster warned against the purchase of equipment for what it may do in the future.
“I think it is a viable option in the future, but right now people are just looking to install one or the other,” he said. “Maybe (SAN and NAS) will converge in the future, but right now people need to make decisions and buy something based on application requirements.”
