Storage Tiering: Making the Most of Your Storage Investment
Storage is a significant part of most IT budgets. As data volumes grow exponentially, new storage technology has evolved to accommodate it—including cloud-based storage, object storage, and distributed storage. Storage tiering is a strategy that lets you optimize the use of storage resources, save costs and make the best use of storage technology for each data class.
In this article you will learn:
• What is storage tiering?
• Advantages of tiered storage
• Cold storage vs hot storage
• The four-class tiered data model
• Tiered storage types: Tier 0-5
• Bridging the hybrid cloud storage gap
What is Storage Tiering?
Storage tiering is a strategy for efficiently using storage technologies according to the business value or importance of the data. A tiered storage system provides several types of storage—for example, SSD disk drives, magnetic disk drives and tape storage. The most important or frequently-accessed data is stored on the fastest, and most expensive media (SSD) and the least important on the slowest, cheapest media (tape).
The minimal storage tiering system has two tiers—one for frequently accessed data and one for archive. The more tiers are available, the more choice administrators have over the placement of specific data classes, and the more efficiently storage resources can be utilized.
Storage tiering is not just about offering different storage technologies. A key aspect of a storage tiering architecture is how to classify data into levels of importance and assign it to the appropriate storage tiers. Over time, data classification can change—for example, as data ages, it may need to be moved into lower tiers or archive storage.
Data classification must be ongoing and must be smart enough to enable rapid classification of large volumes of data.
Advantages of Tiered Storage
Some of the key advantages of tiered storage include:
- Reduced on-premises storage costs—storage tiering makes it possible to purchase less high-performance storage equipment and maintain an inventory or lower-performance, lower-cost storage devices.
- Reuse old equipment—storage tiering enables organizations to use older storage technologies which would otherwise be decommissioned, because they may still be suitable for lower-importance data classes or data intended for archiving.
- Reduced public cloud storage costs—on the public cloud, storage is billed by GB-month, so cost savings translate into a significant reduction in ongoing costs. Leveraging tiered storage on public cloud storage helps organizations pay less, while still providing users with the required level of access for each data class.
Cold Storage vs Hot Storage
A basic distinction in tiered storage is between “cold” and “hot” storage. The following table summarizes the differences between cold and hot data.
|Required Access Speed||Slow||Fast|
|Value of Data||Low||High|
|Storage Media||Slower drives, tape||Faster drives, SSD|
|Storage Location||May be off-premises||Colocated or fast link to the data consumer|
|Cost||Low cost||High cost|
A Four-Class Tiered Data Model
The “hot vs. cold” model is useful but is not granular enough for many tiered storage systems. The following system of four data classes is more expressive:
- Mission-critical data—data required for high-performance applications, where delays can cause damage to the organization.
- Hot data—data in constant use by the business, performance is important but needs to be balanced with cost.
- Warm data—data that may be required by organizational users but is not in constant use. An example might be transactional data from the past week, which is occasionally consulted, viewed or used for reporting. Cost is the primary consideration for warm data, but it must provide reasonable access speeds.
- Cold data—data that is rarely or never accessed. It may only be maintained for regulatory reasons or may be kept because it might have value in the future. In other cases, cold data is maintained to facilitate big data analytics which is not performance-sensitive. Cold data is appropriate for the lowest cost storage tier available.
Tiered Storage Types: Tier 0, 1, 2, 3, 4, 5
Organizations typically maintain up to five tiers of storage equipment.
|Type||Storage Media||Used For|
|Tier 0||SSD, RAM, PCIe Flash||High-performance workloads|
|Tier 1||Fast disks, all-flash storage, hybrid flash storage||Mission-critical or highly sensitive files|
|Tier 2/3||Slow-spinning HDD, disk-based backup appliance, cloud storage, tape||Backups of mission-critical data, which requires high reliability but not instant retrieval from backup|
|Tier 4||SATA drives||Warm data, data used for periodic reporting|
|Tier 5||Tape storage, cloud storage archive tiers (e.g. Amazon Glacier)||Cold data which is rarely or never accessed|
Bridging the Hybrid Cloud Storage Gap with Cloudian
In the modern enterprise, storage tiering has a hybrid cloud angle. Whether data is stored on-premises or already in the cloud, the option of transferring it to cloud storage, or from the cloud to on-premise storage, is always on the table. To utilize storage options to the fullest in a cloud environment, you need granular control over data sets, with the ability to set different SLAs and policies for each data type and class.
Cloudian HyperStore gives you ultimate flexibility for moving data between warm and cold data tiers (tiers 3, 4, and 5). HyperStore offers a low-cost, cloud-scale on-premise storage option, letting you easily move local data to warm or cold storage. It also integrates with public cloud storage systems like Amazon S3/Glacier, Azure Blob Storage and Google Cloud Storage, letting you transfer data on demand to and from the cloud.