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Nov 26 2013

Flexible Quality of Service Management with ETERNUS DX


Since the late 1990s, whenever you ask storage administrators how they handle new challenges, the answer almost always is: "By deploying bigger systems." Simplistic as it seems, this approach is often the only one that works, because along with more capacity, these systems also provide higher data transfer rates and a broader set of management capabilities. On the downside, this strategy causes storage systems and environments to become oversized and underutilized – hardly something you want in a cost-averse economy with shrinking IT budgets.

To help IT departments overcome such difficulties, Fujitsu has developed its third generation of ETERNUS DX arrays. The two entry-level (DX100/DX200) and two midrange models (DX500/ DX600) are the first to use essential Quality of Service functions to ensure fast and stable response times for business-critical applications, but still permit data from lower priority applications to be hosted on the same system. Implementing such functions, however, was previously considered a costly, time-consuming and error-prone process. So why would someone want them in the first place?

Why Quality of Service?
Typically, administrators use Quality of Service functions to ensure a steady flow of data between users, applications and backend systems. Based on a maximum amount of possible IOPS, they will direct the largest data streams to the most business-critical applications and smaller shares to less relevant programs, in descending order. Put another way, they first prioritize business applications and then decide which ones get preferential access to storage resources. In addition, they need to map applications to the adequate storage media, e.g. SSDs, online and nearline SAS HDDs, and tape drives. This, in turn, means they have to build some kind of tiered storage. Up to now, all these actions – prioritizing, mapping, and tiering – were usually carried out at the hardware level, resulting in unwanted complexity and a high error rate. Moreover, IOPS values are hard to relate to actual server or application performance; so they are not reliable parameters to work with. Fujitsu's developers have now eliminated the bulk of these problems simply by automating the key steps. To this end, a set of so-called storage efficiency features was added to the ETERNUS SF management suite.

Increase storage efficiency with AST and Auto QoS
Storage efficiency features is the umbrella term for functionalities that could also be characterized as automated storage resource management. Core elements are:

  • Automated Storage Tiering (AST) – AST monitors data access frequency in mixed environments that contain different storage classes and disk types. The storage administrator does not need to classify data or define policies. Once the tiers are configured, AST controls the destination and arrangement of data, monitors its access frequency, and automatically relocates data to the most appropriate storage device. This hierarchy control reduces storage costs by matching system capabilities and application sensitivity to performance, availability, price and functionality. The automation of tiered storage means that multiple storage tiers can be managed as a single entity. It helps ensure that the right data is in the right place at the right time. AST is also a prerequisite if you want to utilize the second efficiency feature described below. 
  • Automated Quality of Service Management (Auto QoS) – Auto QoS is a tool that was designed to make (storage) administrators' lives easier: it basically covers the same ground as manual QoS management, albeit with a few technical differences. One of these is that it doesn't use IOPS as a parameter, but response times instead. That means users can simply define target I/O response times for physical or virtual storage volumes, based on the relevance of an application or process. As a welcome side effect, response times are also easier to monitor and measure than IOPS. This, in turn, means QoS management becomes easier to automate, as the tool will simply keep track of the response times per volume and eliminate differences between the target and actual values over time.

Availability and pricing
Both AST and Auto QoS are optional features included in version 16 of Fujitsu's management suite ETERNUS SF Storage Cruiser. In this context optional means that users have to buy an extra license to activate these features. For more details, please contact your account manager.

Quintessence: Trends like virtualization and cloud computing not only drive demands for massive storage capacities, but also for a faster and more stable performance of storage systems. To help IT departments fulfill these requirements, Fujitsu introduces its new line of business-centric storage systems together with an enhanced management suite that offers tools for automated storage tiering and quality controls. As a result, storage performance improves; data management becomes easier and more efficient; and IT departments no longer have to worry about the nexus between overprovisioning and underutilization.

For more information, please see the presentations on our Partner Extranet.

What are your experiences with Quality of Service management? Do you think automation makes sense? Which other methods should be used to increase and stabilize storage performance? Please feel freeto comment on these aspects – either below or on our Discussion Board!

Stefan Bürger


About the Author:

Stefan Bürger

Head of Tape Automation at Fujitsu


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