Active vs. Passive Storage Resource Management (SRM)

One characteristic remains constant regardless of organisation type: users leveraging IT deployments generate data and create information. As we turn data into information we create more unique data. The commonality between data and information is that they both need to be stored.

Storage can be within a file system on an individual laptop, hosted on a company intranet or within a corporate relational database. The storage of data or information will usually end up on physical disk, via Direct Attach Storage (DAS), Network Attached Storage (NAS) or Storage Area Network (SAN) attached storage.

The problem faced by organisations of all types is how to predict the levels of data that is being regularly generated and how to match those patterns into available storage or the acquisition of new storage. This requires an understanding of how much storage capacity exists within an organisation. Once the amount of capacity is determined a correlation can be performed between capacity and data.

The best utilisation would be achieve if capacity equals data, but this will rarely happen since you are always generating more data and have a requirement for excess capacity. The results of the correlation typically follow a standard relationship. Smaller companies have a smaller range between capacity and data. Larger companies find they have much greater capacity than data, hence poor utilisation.

Storage Utilisation
Keeping multiple copies of the same piece of data results in using additional space above and beyond the size of the actual data. In a simple disk-mirroring example for every one megabyte of data you will need two megabytes of storage capacity. Therefore only 50% of an organisation's storage capacity would be used to store unique data.

Additional copies of data can be kept for archive purposes, but more commonly these copies are used for data protection and disaster recovery. This is not an incorrect business practice, if it's applied to the correct applications and data types, but does yield lower utilisation rates.

Storage can also be wasted when multiple versions of a file are retained, usually because a newer version of the file exists. Management of the older versions becomes very difficult since there are no standard policies to enforce regarding version management. The version problem becomes exponential when files are being distributed between a group of users within an organisation for review, comment and modification. This results in each reviewer retaining at least two or three copies of the same file, each one with slight modifications.

To gain higher utilisations rates data needs to be profiled and understood. This will determine if too many copies of the same data are being maintained, taking into account that maintenance is not just about storing data, but covers the whole spectrum of data management from fragmentation to backup and recovery.

As the characteristics of the data are highlighted certain attributes draw attention to themselves. For instance, large amounts of aged data, data owned by individuals who are no longer in employment of the organisation, and even large numbers of picture and video files using excess capacity for storage. So, how are organisations going to manage these data storage anomalies and capacity wastage?

Storage Resource Management (SRM)
Storage Resource Management (SRM) is a fundamental requirement for organisations that want to take back control of their data. SRM tools use a mechanism that enables them to discover information about an organisations environment. Once the information is discovered it can then be visualised and viewed. Upon graphical representation of the data, analysis can be performed and recommendations can be reported back. But discovery, visualisation and analysis, is no longer enough for organisations of the 21st century.

Efficiency
Organisations today are not just trying to achieve better utilisation of their storage, efficiency across the whole organisation is a goal that each department has been set to achieve and means managing more storage with the same headcount. It's about having common toolsets that can be utilised across the IT environment regardless of vendor.

Active vs Passive SRM
Efficiency is not about just having analysis and recommendations made as with historic SRM tools, but it's about a new generation of SRM tools that put those recommendations into action. With this new divide between historic and next generations SRM tools we have seen two new categories emerge, the historic category being referred to as Passive SRM and the next generation as Active SRM.

Passive SRM
Passive SRM tools will discover objects within an IT environment and create a static list of objects collected. Once the objects are discovered they are then visualised within a topology map that highlights the relationship between logical and physical objects.

As the relationship is understood between logical and physical, reports are then run that highlight potential areas of concern or typical usage numbers for objects like file systems, databases or physical devices.

Passive in its nature does not actually perform any management, however it does provide a portal to retrieve information if organisations so desire.

Active SRM
Active SRM builds upon the functionality of Passive SRM and intelligently uses the information collected to offer organisations a new level of service. Active SRM does not just make recommendations, it allows organisations to create policies that will proactively modify objects within the environment without intervention required from administrational staff, thus driving down the Total Cost of Ownership (TCO), since less resource is required to manage the environment.

Policies could be as simple as sending notification if a threshold is triggered on a database table or files system or as complex to include the modification of storage network zones and LUN Security characteristic of online storage arrays and host based systems.

Real-time events and performance can be monitored and logged from end-to-end within the storage network from logical applications down to physical devices.

Capacity models can be created by analysing historic data and current storage patterns. The models can then generate scenarios and expectations based on real numbers. The results from the models provide an insight into the future for capacity usage and in turn can highlight problems before they occur.

This allows time to gain better utilisation of existing storage systems or for the chance to embrace adaptive technologies that can exploit sub-systems before they reach full capacities.

Active as in the name, allows active management of storage network environments, allowing proactive configurations to be defined that trigger in the case of known situations arising or notifying when a condition is received that does not conform to standard policy.

Active vs. Passive Comparison
Table 1 clearly shows that Passive and Active SRM both span the spectrum of application, network and storage management, with Passive providing the tools that show a common view into the environment and active allowing the administration to go beyond just monitoring and reporting, allowing policies to be set and modifications to be made.



Conclusions
It is certainly clear that an understanding of data, applications and usage is required to determine how to gain better utilisation. A key driver behind SRM both Active and Passive is efficiency. Efficiency can be gained via: better storage utilisation, shorter data retention periods using online storage, reduced labour requirements and accurate predictions of storage utilisation rates.

Organisations will use a combination of Active and Passive SRM to gain better control of their environments, enabling them to drive up the utilisation rates and have better control of not just the storage but also the data and it's fundamental characteristics. Organisations are not satisfied with just monitoring and reporting and now have a need to take corrective action, in this case ACTIVE SRM.