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Implementing NAS Clustering – Questions to ask

What are the storage options in terms of SAS, SATA and Fibre Channel drives, or solid state drives, for the solution?

• How disruptive will it be to add new storage or replace existing storage?
• How disruptive will it to be to add storage to the NAS cluster or add NAS boxes to the a cluster?
• How are files spread across different nodes and the storage environment for access, capacity and availability?
• Which automated load-balancing features (performance, access and capacity) exist?
• Does a file system exist on one node, or can it be active across multiple nodes concurrently?
• Can storage be accessed by all file server nodes without shipping I/O between nodes?
• Are host software clients, agents or file systems required on either the client or the application servers?
• How does a NAS clustering solution leverage more nodes, processors, memory, networks and disks?
• What is the performance for different types of data access, such as large files? What about small files?
• What is the maximum amount of storage, file system size, file size and number of files supported?

Comment

More processors should equate to better performance. However, it comes down to how those processors are used by the software that determines actual performance. The best benchmark comparison is your own application running in a real world scenario or in lieu of that, looking at relative comparisons, such as specifications.

Your needs will ultimately determine whichever NAS cluster configuration you decide on. One myth about clustered NAS file serving solutions is that they’re designed for high performance computing infrastructures. But not all clustered storage is targeted for high performance, and there are some high-performance storage systems that do not scale well. Do your homework and align the right type of clustered file serving solution to meet your particular needs and requirements.

Dispelling myths about clustering NAS and file servers

worth a read ……….

http://searchstorage.techtarget.com/tip/0,289483,sid5_gci1307947,00.html

 

Myth: More ports, processors, nodes, networks and devices guarantee more performance.

It’s not just about the number of components or speeds and feeds. More nodes, ports, memory and disks do not guarantee more performance for applications.; It depends on how those resources are deployed and how the storage management software enables those resources to avoid bottlenecks. For some clustered NAS and storage systems, more nodes are required to compensate for overhead or performance congestion owhen f processing diverse application workload and performance characteristics

NAS

While clustered storage is often associated with high performance computing, the reality is that organization are adopting adopting clustered storage at a rapid rate.

 These organizations are attracted by the way clustered storage uses technologies

• Ethernet,
• Fibre Channel
• InfiniBand protocols,

by its reliance on open access methods such as NFS and Windows CIFS, and by its use of industry-standard servers and third-party storage.

The clustered storage solutions that are growing in popularity are network attached storage (NAS) file servers. Deployments of this technology are being driven by the need of organizations to scale beyond the limits of a single storage box to handle structured and unstructured data.

Clustered NAS systems offer scaling advantages on many levels:

• scaling in performance of large sequential bandwidth (throughput) or small random IOPS (transactional) and meta data lookup;
• scaling in storage capacity;
• scaling availability on a local or distributed basis to isolate against device or site failure;
• scaling of flexibility, including concurrent access of the same or different data along with parallel access of data for different application needs;
• scaling in terms of offering modular (pay-as-you-grow) storage growth; and
• scaling in ease of manageability of tasks such as provisioning of storage, load balancing and data protection.

Approaches to NAS and file serving clustering

The technologies that most companies are clustering are storage, file systems and file servers.

Clustering adds standby or failover capabilities to storage systems that in turn support scaling with a large number of controllers, storage nodes or processors along with clustered file systems.

One reason for the confusion in discussions of clustered storage is that there are block-based (iSCSI and Fibre Channel) and file-based (NAS NFS and CIFS) storage, virtual tape libraries and other types of clustered storage solutions.

Clustered file systems enable administrators to access a common pool of storage across application servers. Clustered file systems also permit shared access (read and write) of data files, which is useful for maintaining data consistency and integrity whether using direct-attached or networked storage.

What differentiates a clustered fileserver from a traditional NAS file server or clustered storage system is the way hardware and software is combined.

A clustered file system can be installed on application servers or on dedicated appliances or servers, transforming them into storage servers (essentially, becoming a clustered fileserver).

Some vendors who have dual or redundant storage controllers, storage engines, NAS heads or gateways using active/active (both controllers working) or active/passive (one controller in standby) modes claim to offer clustered storage systems.

A pair of storage processors or controllers as a cluster, you’d have to consider every storage system with at least two nodes a cluster. . .which would encompass pretty much all of the mid-range SAN, DAS and NAS storage systems in the marketplace.

NAS, by its nature, is a file serving solution that sits on top of hardware and in some cases has the ability to transform the hardware into a clustered fileserver