George,
Regarding VI, here's the FAQ from Intel. Release 1.0 of the VI spec was issued in 1997, but it hasn't really been commercialized yet so the QLGC/NTAP collaboration is interesting. I'm still looking for information comparing NTAP's DAFS with VRTS' GFS as well as future iterations of UNIX's NFS and Windows' CIFS. Let me know if you come across anything across those lines. TIA.
What is the Virtual Interface (VI) Architecture?
The Virtual Interface (VI) Architecture is an open industry specification that defines an interface for low-latency, high-bandwidth communication between servers and storage devices within a cluster. It enables the construction of clusters around the common, volume building blocks of standard high-volume (SHV) servers and commercial, off-the-shelf operating systems.
Is VI Architecture a new network?
No. The VI Architecture specification is processor, media, and operating system independent. VI Architecture defines the interface to the networking hardware, not the networking hardware itself.
What is a cluster?
A cluster is a group of servers, workstations, and storage subsystems that are linked together by a SAN so they act as a single, large computing resource.
What is a SAN?
The term System Area Network, or SAN, refers to the high-performance network that interconnects the servers and storage devices within a cluster. VI Architecture defines the interface that operating systems and applications use to communicate with each other through the SAN.
Note that a SAN does not connect the servers and storage within a cluster to the client nodes outside of the cluster. Standard LAN/WAN hardware is used for that purpose.
What are the benefits of clustering?
Clustering offers three primary benefits: scalability, availability, and manageability.
Clustering offers scalability by allowing multiple SHV servers to work together. The cluster combines the processing power of all servers within the cluster to run a single logical application (such as a database server). Furthermore, additional processing power can be easily provided by adding servers to the cluster.
Clustering offers availability by allowing servers to "back each other up" in the case of failure. When a server within the cluster fails, another server (or servers) picks up the workload of the failed server. To the user, the application that was running on the failed server remains available.
Clustering offers manageability by providing a "single system image" to the user of the cluster. The user sees the cluster as the provider of services and applications. The user does not know (or care) which server within the cluster is actually providing services.
In the past, these benefits (scalability, availability, and management) were only available as proprietary solutions. With clustered SHV servers and workstations, these benefits are now available at much lower price points using industry-standard, volume components.
Is clustering a proven technology?
Yes. Clustering has been around for years in the enterprise systems market and has been used successfully to run large applications such as data warehouses, decision support systems, and online transaction processing systems that have requirements for high availability or "out of box" scalability.
If clustering has been around for years, what does the VI Architecture specification do that existing clustering solutions do not accomplish?
VI Architecture allows users to capitalize on the cost savings, flexibility and versatility that are fundamental in the high-volume computing market segment. VI Architecture effectively brings volume technologies to clustering to address enterprise requirements. In the past this has only been available on costly proprietary systems. VI Architecture brings the scalability and reliability benefits of proprietary solutions to the volume server and workstation industry for the first time.
How does the VI Architecture specification offer these new benefits?
Creating a high-performance, scalable cluster requires the following two communications ingredients:
The ability to pass large amounts of data between nodes in the cluster ("high bandwidth").
The ability to pass messages quickly between nodes in the cluster ("low latency").
Prior to the release of the VI Architecture specification, communication between nodes in a cluster was done through the network infrastructure provided by the host operating system. The operating system infrastructure required large amounts of processing overhead to send each message. This overhead limited the bandwidth and increased the latency.
The VI Architecture specification reduces the latency and increases total bandwidth by significantly reducing the overhead of the traditional network infrastructure in the operating system. In its place, the specification defines a thin, fast interface that connects software applications directly to the networking hardware while retaining the security and protection of the operating system.
By enabling more robust cluster communications, enterprise applications that have traditionally been limited to large, proprietary, legacy systems can now be moved to large-scale, high-volume, SHV clusters.
Who created the VI Architecture specification?
VI Architecture was created by Intel, Microsoft, and Compaq with over 100 companies contributing. A complete list of contributing companies can be found on the VI Architecture web-site at viarch.org.
What is the current status of the VI Architecture specification?
Version 1.0 of the VI Architecture specification was released to the public on December 16, 1997.
How can I get a copy of the VI Architecture specification?
Visit viarch.org.
How many servers/processors will you be able to cluster using VI Architecture?
VI Architecture imposes no upper limit on the number of servers that can be interconnected.
Do applications need to be rewritten to take advantage of VI Architecture?
No. In the traditional enterprise "software stack" there are three layers: a specific application is written to run on a generic database server that runs on the host operating system. In general, only one of these layers needs to be VI Architecture conformant to get the benefits of VI Architecture. The following example explains how this can be done:
A VI Architecture-aware database server can offer scalability benefits by being written to parcel out large queries across several nodes in the cluster. The application that issues these queries does not need to be VI Architecture-aware—all the application is concerned with is that the database server can perform the query. The application benefits by receiving the response to its query in a fraction of the time. Furthermore, scalable, clustered databases can run on standard, non-clustered operating systems as well.
What are the benefits of VI Architecture to end-users?
The VI Architecture specification provides a single, industry-standard high-speed cluster communication interface that promises substantial benefits for distributed enterprise computing. It will enable the construction of clusters around the common building blocks of standard high-volume (SHV) servers and commercial, off-the-shelf operating systems. This new paradigm is expected to deliver the enterprise-class scalability, reliability, availability and manageability that businesses need for high-performance, mission-critical applications—at a fraction of the cost of traditional, proprietary mainframe and RISC-based clustering technologies.
Clustering systems provides more availability and manageability by allowing workloads to be easily moved between different servers without impacting users. It can also provide a simpler, more cost-effective way to scale up server resources by simply adding SHV servers to the cluster and using applications that can dynamically spread the workload across all available servers within the cluster. VI Architecture will make this more practical for the end user to implement in the future because of the standards-based approach it brings to the industry.
What are the benefits of VI Architecture to OEMs?
The VI Architecture gives Original Equipment Manufacturers (OEMs) a framework for designing and building low-latency, high-reliability clusters for high-volume markets. The economics of volume allow OEMs to manufacture clustered systems at very low costs, while surpassing mainframes and supercomputers in performance and reliability.
What are the benefits of VI Architecture to IHVs?
In the past, each SAN interconnect vendor designed a unique, proprietary interface for applications and operating systems to use. Given the proliferation of non-standard, proprietary interfaces, application and operating system vendors had to either choose a specific SAN vendor to partner with or spend significant resources trying to support multiple incompatible SANs. Given these conditions, SAN vendors had a difficult time gaining market acceptance for their products.
With VI Architecture, all SAN vendors can now design to a single communications interface that will seamlessly interconnect with all VI Architecture-conformant applications and operating systems.
How will this Specification benefit the industry?
Developing an open specification helps to lower costs for all suppliers in the industry. The Specification provides a common base to which all parts of the complete integrated solution—communications technology, hardware components, systems software, and application solutions—can be developed and optimized for.
Why do we need a commodity clustering solution?
Open specifications provide users with lower costs of acquisition and support, plus more choice in providers of systems, applications, and services. A commodity solution also provides a common platform to foster industry cooperation and innovation.
What is Intel doing to support companies developing VI Architecture-conformant products?
Intel is in the process of developing tools to assist the industry in developing products that conform to the VI Architecture interface referenced in the specification. A preliminary version of the Intel VI Architecture Implementation Guide is available today. Other tools, such as performance and conformance tests, will be available in the near future. As these tools become available, they will be posted to the Intel VI Architecture developer web-site at intel.com.
How do I find out more about VI Architecture?
Intel, Microsoft, and Compaq have set up an independent VI Architecture web-site at viarch.org.
qlogic.com |
