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As more Russian companies adopt virtualisation in their datacentres, the need for optimised virtual machine storage is increasingly relevant.
Russian IT managers are well aware that traditional spinning disk hit a performance wall a while ago, especially with regard to supporting virtualised environments. The mechanical seek heads of the HDD simply can't cope with the volume and random nature of storage I/O demanded by virtual servers and desktops.
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So, virtualisation has created new challenges for companies’ IT infrastructures. Most Russian companies have adopted virtualisation and the number of servers and desktops going virtual is constantly rising.
But virtual machine storage on spinning disk is problematic. Because of their mechanical nature, disks are too slow to handle random I/O, and spend far more time looking for data than actually reading or writing it. There is no fix for that problem because spinning disk will not get any faster.
A key issue is the so-called I/O blender, which refers to the extreme randomisation of virtual machine I/O as many virtual machines all try to access storage simultaneously.
All-flash storage resolves the I/O blender issue, largely by being able to offer stunning performance – up to and exceeding 1 million input/output operations per second (IOPS).
Recently, all-flash storage arrays have become a popular solution on a global scale, with architectures designed from the ground up for flash and providing rapid-access, solid-state storage.
But all-flash arrays come with a heavy price tag, which puts them out of the range of all but the deepest-pocketed organisations in Russia, such as the local division of Austria’s Raiffeisenbank or insurance behemoth Ingosstrakh, which recently announced a switch to all-flash storage.
A handful of other companies in the banking and telecoms sectors have also taken the all-flash array path. But for smaller companies, hybrid solutions offer a more viable option.
This approach does not provide the highest levels of performance, but it offers the ability to move low-latency storage to where it is needed for key applications.
Often, automated storage tiering that pushes the hottest data to a flash tier that comprises a small percentage of overall capacity is used to achieve that. Several manufacturers, including EMC, Hitachi Data Systems, IBM and HP, offer hybrid solutions.
Kaspersky Lab, a prominent anti-virus software developer, mostly uses entry-level and mid-sized IBM Storwize hybrid systems for virtual machine storage.
“The main selection criteria were price, performance, reliability and simplicity of technical support,” said Ivan Moshkarin, R&D services infrastructure development group manager at Kaspersky.
Flash storage is used by the company for specific tasks where uncompromising high productivity for relatively small data volumes is required, he adds.
One example is to host virtual machines with databases or for temporary intense peak loads for some critical virtual machines, says Moshkarin.
High prices among disadvantages
“The advantage of flash storage is the very high speed of data processing and compact size of the arrays,” he says. “High prices are among the disadvantages.”
According to Ilya Vladimirovich, head of the virtualisation department at consulting company LANIT-Integration, the choice of virtual machine storage solution is largely determined by specific tasks.
“Unfortunately, there is no universal solution at the moment that can satisfy different needs,” he says. “In any case, when choosing a solution, there is a need for balance between price and compliance with technical requirements.
“The only hope is for new software-defined solutions, but in most cases, they are still rather raw.”
Vladimirovich adds that only companies that already have substantial expertise have been successful with software-defined solutions.
In Russia, he says, traditional data storage systems in the mid-range price category remain the most popular for virtual machine storage, but sales of that kind of equipment have been declining.
“It is most likely happening because smaller companies tend to move their infrastructure to clouds and large companies with far-flung networks of regional branches choose consolidation and creation of private clouds,” says Vladimirovich.
“Flash storage is a rather niche product [in Russia]. True, they are used by some companies, but not very often because of high prices. They are mostly used in large VDI projects.”
According to Vladimirovich, in the enterprise segment, hybrid systems are a quite common solution for virtual machine storage that can achieve decent performance from a relatively small investment compared with high-end storage solutions.
Gas processing and petrochemicals company Sibur uses EMC’s VNX2 and VMAX hybrid arrays.
“We primarily look at criteria such as performance, price and scalability,” says Pavel Klepinin, Sibur’s director for information technology. “Balance of configurations is also a major factor.”
High storage density
According to Klepinin, the main advantages of hybrid flash arrays are their high storage density and automatic data balancing based on usage and scalability. “However, they also have noticeable drawbacks, such as limited performance and absence of storage virtualisation.”
Having said that, the existing solutions available still provide challenges related to virtual machine storage, says Klepinin.
Among the challenges Sibur has faced when providing virtual machine storage is the need to constantly control traffic so that when virtual machine I/O overloads storage on one array, it can be offloaded to other systems, he says.
“Another challenge is to control the storage room as virtual machines grow in size and to add new storage capacity in a timely fashion.”
For Sibur, the main challenges in virtual machine storage are high costs of virtualisation, data repetitions and I/O limitations, Klepinin adds.