By Danny Bradbury, Contributor
Storage resource management, or SRM, software has come a long way. And it's no surprise it has done so as storage has evolved from direct-attached drives to shared storage that supports virtual server environments.
The main development in SRM software in the past couple of years has been the ability to analyse and manage storage used to support virtual server environments. Server virtualisation affects storage configuration and performance in ways previously unseen. Because it is so easy to spawn new virtual machines, organisations can find VMs proliferate on their SANs, leading to bottlenecks, rapid increases in capacity usage and unused VMs that were created for one-off tasks and never deleted.
Dharmesh Bhatt, lead storage engineer at data centre operator Colt, has first-hand experience of the added urgency a virtual server environment brings to managing storage.
"Data stores might not be configured correctly, or they might not point to particular servers. Because it's so easy to provision storage, it can be a bit difficult to keep a handle on it. VMware software doesn't do this, although you'd think it would," he said.
Bhatt manages storage across three data centres. A development facility in Amsterdam complements two operational buildings in London, each containing around 50 TB of storage. This is split among four Clariion boxes in each facility.
Bhatt needs to analyse storage to evaluate baseline capacity. He needs to understand what is held in each array and how much free space is available. It's particularly important to be able to free up space not being used in the array, because Colt's move to virtualised storage and consolidated servers has led to a rapid growth of the physical boxes it owns.
"For us, the virtualisation space is the fastest-growing," Bhatt said. "Our VMware ESX servers are growing very quickly. They have expanded by 6 TB alone in the last month."
In the past Colt was able to get away with relative inefficiencies in the way it analysed its storage baselines. Before the company took a more automated approach to storage resource management, it relied heavily on scripts written by staff, but the time involved in manually crunching the numbers became increasingly onerous. Like many, the data centre firm has to do more with fewer people in a recessionary environment.
"This collection of scripts analysed the storage arrays manually, and then we'd pull off a large amount of data and spend hours in Microsoft Excel creating graphs," Bhatt said.
The company's own scripts were fine in non-virtualised, direct-attached storage environments, but it needed a more robust solution as its infrastructure became more sophisticated. Colt tried EMC's storage resource management and reporting tool, StorageScope, part of its Ionix ControlCenter SRM product, but Bhatt found it time-consuming and difficult to configure. Instead, the company opted for Storage Resource Analysis (SRA), a tool from Storage Fusion that enabled Bhatt to quickly understand the state of his virtualised arrays.
This service-based form of SRM software enabled the company to quickly run scripts that Bhatt's team had downloaded, extract the numbers from Colt's arrays, then upload the data for remote analysis on Storage Fusion's servers.
"Getting the data isn't difficult; it's the analysis that takes forever because you have to put it in the correct format and get the dates you're interested in," Bhatt said of his home-baked data retrieval scripts. By using storage resource analysis scripts from Storage Fusion, he could drastically reduce that time. "The scripts take about five minutes to run, and then we FTP the data."
Bhatt is then able to access a Web portal that allows him to examine storage data trends over a period of time.
Bhatt's experience shows what can be done with a service-based approach to managing storage for virtual servers.
It's an approach that reflects the lack of a unified solution to the problem of monitoring and management from the vendors of storage and virtual server environments. Given that this divide is a commercial reality, it is likely that integrated vendor solutions across both product sets are some way off and such point solutions will be here for some time to come.
This was first published in January 2011