A simple guide to thin provisioning
How to increase utilisation and save money
By Galvin Chang, Infortrend Technology | Network World US | Published: 14:00, 07 March 2011
While provisioning all the capacity of an external disk to a given application, known as full provisioning, ensures an app has plenty of growth potential, it results in poor utilisation rates, a costly problem that can be addressed with thin provisioning technology.
Research shows that storage utilisation rates achieved by most companies is 40% or lower. That means buyers are acquiring more capacity than they really need, and the very existence of that extra capacity requires more space and cooling.
Furthermore, the traditional method of provisioning leads to increased management workloads, due to the fact that the extra but unused capacity still needs to be monitored and managed. If applications reach their capacity limits and IT managers have to re-provision capacity, complex management tasks can be involved. More management requires more human resources, further driving up costs associated with storage management.
Additionally, if an application is taken offline to reprovision capacity, it is then unable to serve business needs and can lead to revenue loss.
Addressing the hardware problem
Thin provisioning provides a way to address these limitations. By automatically allocating system capacity to applications as needed, thin provisioning technology can help achieve up to 90% storage utilisation, while at the same time significantly reducing power consumption.
Thin provisioning allows users to allocate a large amount of virtual capacity for an application, regardless of the physical capacity actually available. At initial setup, thin provisioning does not physically allocate capacity to the prescribed data volume, and the actual space is used only when data writes occur.
This on-demand method for capacity allocation not only optimises storage utilisation, but also greatly simplifies capacity planning and management. In order to help users easily monitor capacity utilisation, storage systems automatically issue notifications when the total capacity utilisation is reaching the threshold set by the user. If users wish to expand capacity, they can do so non-disruptively.
With traditional provisioning, it is difficult to move data across logical partitions in a storage architecture. If thin provisioning is applied, storage capacity from different logical partitions can be consolidated, enabling it to be dynamically allocated. From the opposite perspective, this means that the storage controller can move data dynamically across logical partitions based on how resources are designed to function.
Furthermore, thin provisioning opens the door for other advances in storage design, including automated storage tiering. Storage tiering involves grouping data into different categories and assigning these categories to different types of storage media in order to optimise storage utilisation.
Automated tiering ensures applications have access to the performance levels they need. High performance applications can be assigned to high performance tiers featuring drives such as SSDs or SAS, while applications requiring less performance can be assigned to lower tiers featuring low performance drives such as SATA.
This ensures that no storage resources are wasted and that applications can function properly. In addition, this technology helps automatically migrate data based on usage patterns. If data in higher tiers has not been used for an extended period of time, it is demoted to lower tiers. Conversely, if data in lower tiers is frequently accessed, it is promoted to higher tiers. Storage efficiency can be greatly improved with this technology.
The benefits in a nutshell
In terms of tangible benefits, the overarching result of using thin provisioning is it helps significantly reduce costs. With thin provisioning, utilisation can be greatly increased and you can get more out of your existing capacity, reducing the need to add new HDDs (hard disk drives). This can generate significant cost savings, which can be particularly important for companies with limited budgets.
These benefits are highlighted by the figure below. With thin provisioning, capacity is dynamically allocated to applications from a consolidated storage pool, eliminating the need for the allocated but unused capacity in full provisioning.
The benefits of delaying new HDD acquisitions are further magnified by the fact that HDD prices continue to decline. Delaying acquisitions thereby becomes even more worthwhile.
Another major benefit is power consumption can be reduced considerably, leading to more cost savings. Since you do not need to buy as many HDDs as before, the rack space needed for a storage solution can also be reduced.
Storage management also becomes much easier with thin provisioning. There is less to manage with a smaller number of HDDs, and you spend less time allocating capacity to applications. Furthermore, when capacity limits are reached, capacity can be added nondisruptively, eliminating the hassles associated with downtime.
If you end up turning to thin provisioning for the benefits outlined, here are a few tips to help you get the most out of the technology:
- Claim as much virtual capacity for applications as possible. This reduces management tasks and ensures applications have access to sufficient capacity as long as physical resources are available.
- Monitor physical storage capacity utilisation. Even though large virtual capacities can be allocated, each storage pool still has physical limits. Monitoring physical capacity utilisation is thus extremely important.
- Set physical capacity utilisation thresholds based on pace of data generation. By creating notification mechanisms for when these thresholds are reached, sufficient time will be available to properly plan storage expansion. Setting a correct threshold is most important. For example, if an application fills 10% of capacity within only a few days, setting the utilisation threshold at 90% could lead to major problems, as the user will not have enough time to plan capacity expansion in order to ensure that an application can continue to operate normally.
The benefits of thin provisioning are numerous and can generate considerable cost savings. With thin provisioning technology now widely available in the storage market, it should be a key consideration for companies planning to acquire new storage solutions.