Expert advice: What NAS gateways are all about |
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By SearchStorage.com editors
12 Feb 2004 | SearchStorage |
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SearchStorage.com has received many questions from our readers on NAS gateways and what's in store. As a result of those questions, we asked our NAS expert Randy Kerns to share his thoughts regarding the ease of NAS gateway implementation, why you might want to consider a gateway, how it will be managed and what products he sees coming down the road.
Some vendors are saying that it's possible to drop a NAS gateway into an existing SAN. Is it as easy as that? And what about the costs?
Yes it is possible to put a gateway into an existing SAN and that is the primary way they are being deployed. Usually, some LUNs on a storage system are allocated to the gateway to use for filesystems and the NAS gateway treats them like dedicated devices. The administration differences are in setting up the LUNs in what is typically a resource shared storage system.
The cost savings are in the use and administration of the storage system that is part of the SAN and provides block data either for the SAN-attached servers or the SAN-attached gateway that provides the remote file system for IP-attached clients. The numbers are highly dependent on the environment but usually a gateway is used for consolidation of many independent file servers to a single, IT managed environment that can result in large administrative cost savings.
How easy/difficult will the gateways be to manage?
The storage resource (the block I/O device) will be managed as any storage device in the SAN. The gateway will be administered like a typical NAS device with the LUNs provided appearing to be captive storage. It should be nearly as simple as any NAS device.
What would be the primary reason to attach a gateway to an existing SAN?
The primary reason is to utilize the SAN storage resources for the block storage used by the NAS controller function. This is normally driven by the economics of consolidating file servers for administration purposes.
What are your views on SAN/NAS unified storage vs. NAS gateways?
I am generally a skeptical person, which is necessary when dealing with so many marketing people. In addition to that, I've spent a great deal of time in my past engineering development career dealing with performance issues for storage systems. Unified storage is one area where there hasn't been enough time to accumulate data about performance when there is a mixture of file and block access in a single system. Typically these systems have a single cache and I have yet to see any controls where I can influence the priority or caching amounts given to one type of access versus another.
Make no mistake, the characteristics of the data access (locality of reference, sequentiality, etc.) is very different between them so the same caching and prioritization algorithms will not produce an optimal performing environment. This is why I hesitate on these solutions. We really need to do some real world experience, data and benchmark testing (and not bench marketing) in order to know the effect.
What gateway products, if any, will we see coming into the 2004 market?
IBM has announced the Gateway 500G product that is now becoming available, Network Appliance is qualifying additional storage system attachments for their gateways called gfilers and EMC just announced the NS700G gateway product. Other vendors such as HP have gateways and regularly update their product families.
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