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Telescope 2007

Storage: Getting the most from your SAN

Three-tier architectures with a Web-based front-end, an application server and a database server are commonplace. With an increase in the number of users, more data being stored at the back-end, and a consequent rise in the number of requests that a database server has to address, it is harder than ever to figure out where a bottleneck lies in this tangled mess. But solutions are available in the market that help CIOs optimise application performance. Vendors also suggest certain best practices which can help squash the speed bumps in an enterprise data centre. By Rishiraj Verma and Aishwarya Ramani

A company’s growth is almost always the reason for bottle-necks. Along with organisational growth, the data that is accessed daily by its employees also grows. This translates into more users concurrently trying to access data. One way out is to adding devices to the storage sub-system. However, in a traditional file server environment, adding storage devices may increase an administrator’s burdens and may have an adverse impact on performance and device availability.

Says Manish Bapat, National Manager, NAS and CAS, EMC India and Saarc, “As requirements grew, companies bought more devices.” Data in such cases tends to be accessed from each device separately. The picture changed when the concept of networked storage was introduced, i.e. SAN and NAS. This wasn’t however a final solution to these problems. Data growth did not stop and the need for innovation was felt again.

Ketan Parekh

It is this constantly growing data that may be a cause of further concern. According to Ketan Parekh, CTO, Sharekhan, “One of the critical problems while dealing with networked storage is accurately estimating the growth or throughput of data.” He is of the opinion that a correct estimate here can help in getting the right number and size of the discs that need to be used as part of the SAN.

Neeraj Matiyani, Business Manager, StorageWorks Division, HP India, concurs with Parekh’s view. “Improper planning of the network is a contributing factor to bottle-necks.” Most organisations face this problem because growth may exceed expectations. The first step is to understand how much data may be generated and accessed in the near term, and there is no room for miscalculation during this step.

Soumitra Agarwal

Improper classification of data in the earlier stages may be the cause of grief down the line. Says Soumitra Agarwal, Marketing Director, NetApp India, “Unstructured data accounts for about 75 percent of an organisation’s storage capacity.” He insists therefore that issues of classifying, indexing and moving unstructured data to lower-cost tiers must be addressed well in time.

There might also be a sudden increase in the volume of data being accessed over the network. An increase in the number of users, or again, the growth of the organisation, could be the probable causes of this condition. Says Shailesh Agarwal, Country Manager, Storage, IBM India, “If the data is old and is no longer being used, then archiving it to tapes would be the most viable option. However, in the case of critical data, transferring it to lower-cost SATA discs with the use of technologies such as storage virtualisation would be ideal.”

Third-party solutions for tracing application bottlenecks
CA Enterprise IT Management It enables management control across the enterprise by integrating and automating the management of IT applications, databases, networks, security, storage and systems across departments and disciplines. It addresses the needs of businesses in four main categories: business service optimisation, enterprise systems management, security management and storage management. This integrated approach to IT management helps identify bottlenecks.
Symantec i3 The solution captures metrics for monitoring and tuning multi-tier applications. It provides a view of how applications are performing from an end-user's perspective. It also delivers the information needed to fine-tune applications by pinpointing friction points in the end-to-end path across multiple tiers; provides the ability to drill down into hot-spots to identify the application-specific concerns; offers best practice recommendations; and enables the easy validation of the effectiveness of any corrective action taken.
Zenith SAAZ This remote IT management tool looks at various parameters, and monitors processes to help figure out where a problem lies. It combines an IT management platform with a secure remote access technology. It combines desktop, server, network and application management into a single integrated system.
HP OpenView The Infrastructure Optimisation Management layer in HP's OpenView takes care of issues like virtualisation, performance management and end-to-end user application performance management. HP Application management solutions enable administrators to build manageable applications, optimise them in pre-production, and manage the entire application environment in production from both an end-user and infrastructure perspective. Users can drill down to the component or even the method level of the application to determine the root-cause of a problem.
IBM Tivoli Business Application Management It helps ensure availability and performance of business-critical applications, including portal and service oriented architecture-based technologies. It also assists in planning, management and optimisation of a customer's software assets. The solution helps customers quickly isolate, diagnose and fix business-critical application performance problems. When an incident occurs, the Tivoli solution helps resolve it by facilitating the information flow between operations, development and support groups.

A potential answer

Virtualisation, in one form or the other, has always been considered key to reducing IT-related costs and increasing efficiency. In the case of SANs too, virtualisation can help cut down on an administrator’s list of problems

Once the CIO has identified the storage needs, he needs to look at ways of ensuring that the infrastructure is used optimally, without the need for further expenses and increasing efficiency.

Virtualisation, in one form or the other, has always been considered key to reducing IT-related costs and increasing efficiency. In the case of SANs too, virtualisation can help cut down on an administrator’s list of problems. It can also help drastically reduce the complexity involved in creating, editing and deleting files and applications over a network.

With regard to SAN optimisation, Global Namespace (GNS) seems to be something of an answer to a CIO’s troubles. GNS is a logical layer that is inserted between clients and the file systems so that users can access data independent of where a physical file is located.

GNS uses a set of paths and file names (in the form of URLs) that help access specific data. Clients can use the same path for the data, regardless of its geographical location. However, the use of the same path to access data does not mean that the same caches are used to route all requests. As Soumitra Agarwal explains, “A GNS is separated from the actual components—clients, caches and servers that it is built from. It is a one-to-one mapping between a piece of data and the path to it.”

CIOs seem to be welcoming this idea. Parekh feels that GNS is a good concept because “it shields the end-user from the changes taking place in the storage set-up where data resides.” In effect, GNS does much the same thing for storage that DNS does for networking. Clients are able to access data without knowing where it is in the same manner that users access a Web site without knowing its IP address. Apart from helping users, this also helps administrators add, change, move, and reconfigure physical file storage without affecting how users view and access the same.

Vivekanand Venugopal

Vivekanand Venugopal, Director, Software Solutions, APAC, Hitachi Data Systems, is upbeat about it: “It (GNS) is an optimisation technique and will prove to be the future of file management.”

On the other hand, Sumit Mukhija, Business Development Manager, Cisco Systems India & Saarc, takes the concept with a pinch of salt. “It’s a great concept, but it’s still a concept.” According to him, there is not much happening in the market as far as GNS offerings are concerned.

GNS aims to change the way files are managed over a network. Its other goals are to raise data utilisation, cut down on over-provisioning, and resolve bottlenecks without necessarily having to add discs and arrays to a SAN. GNS helps administrators support heterogeneous storage environments. The concept also aims at optimising networked storage across different vendor platforms and storage tiers.

Native Performance Tuning Tools (Server OSS)
Server OS
Software to spot bottlenecks
Sun Solaris 10 Dynamic Tracing (DTrace) Helps developers rapidly identify the root-cause of system and application problems. Resolving system or application performance bottlenecks can be reduced from days to hours. Can be used safely on production systems. DTrace's single view of the software stack simplifies the tracing process, enabling developers to follow a thread as it crosses between kernel space and user and back.
Microsoft Windows Server 2003 Windows System Resource Manager (WSRM) WSRM lets you set CPU and memory allocation policies for applications. This includes selecting processes to be managed, and setting resource usage targets or limits. It also allows the user to manage CPU utilisation. It allocates resources through server consolidation to reduce the ability of applications to interfere with each other. WSRM can be administered using two different interfaces: the graphical user interface (GUI) and the command-line interface (CLI). The GUI is provided by an administrative snap-in. The CLI enables command-line scripting and supports advanced uses. Both user interfaces provide access to the full functionality of WSRM.
IBM AIX AIX Workload Manager (WLM) WLM delivers automated resource administration for multiple applications running on a single server. This capability helps to ensure that critical customer applications are not impacted by the resource requirements of less-critical jobs in the system. The policy-based architecture of WLM allows systems administrators to spend less time on routine workload management tasks by automatically applying individually-tailored resource allocation profiles.
Red Hat Red Hat Enterprise Linux Monitoring Module The monitoring module allows users to track the performance of the Enterprise Linux systems. It helps in receiving alerts regarding system performance, allowing you to take action before problems arise. It creates custom probes for applications not included in the pre-built probe set, and configures warning and critical thresholds for each probe. Administrators receive e-mail or pager alerts when thresholds are reached.
HP HP-UX 11i HP-UX Workload manager (WLM) With HP-UX WLM, users can define objectives with a priority which they can then assign to a WLM workload. HP-UX WLM provides a passive mode that allows users to see how it will approximately respond to a given configuration. Users can control Oracle database instances, adjusting their CPU allocation-based desired transaction response time, the number of users connected, etc. WLM and its SAP Toolkit enable users to identify different SAP processes or instances and place them into separate workloads.
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