Thin Provisioning Explained

In our current digital age, enterprise file sizes and data needs are ever-increasing—meaning managed services providers (MSPs) need to find the right storage solutions for ever-changing client needs. An ideal storage system has sufficient capacity for large amounts of data, but avoids excess capacity to be efficient and cost-effective.

Fortunately, today’s technology uses storage media efficiently to enable more data with less space. Thin provisioning is an excellent way to accomplish this. In this article, we’ll explain how thin provisioning storage works, how it compares to thick provisioning, and how it can serve your clients’ storage needs.

First, let’s examine thin vs. thick provisioning.

What are thick and thin provisioning?

Thick and thin provisioning represent the two rival ways to allocate storage space in centralized disk storage systems, storage area networks (SANs), and storage virtualization systems. Thick provisioning—also known as fat provisioning—is the more conventional method. Using thick provisioning, storage space on physical media is allocated to particular users when their drive partition is created. A set amount of storage resources are reserved for each user, regardless of how much space they are actually using.

Consider an office with multiple users who each need up to 50GB of network storage. The office has a 100GB hard drive on the network. With thick provisioning, only two users could fit on the drive. Even if one was merely using 10GB of space, they would still take up half of the drive.

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Thick provisioning allocates storage space up front in anticipation of future needs, which can cause inefficiency and wasted space. If users only fill up a small portion of their quota, the rest of the space on the drive remains unused. The business must pay to maintain this excess hard drive or solid state capacity, which takes up physical space, uses energy, and generates heat. On the other hand, the advantage of this pre-allocated space is that it guarantees there will be enough capacity available. The network will not run out of space even if both users approach their complete 50GB quota.

What is thin provisioning? Also known as virtual provisioning or thin storage, thin provisioning is the rival disk provisioning method. Thin provisioning allocates disk space to users on demand based on how much space they need at any given time. As a user saves more data, they take up more of the disk; when they delete data, their portion shrinks. Divisions on physical storage are virtual and flexible rather than determined in advance.

Consider our previous example. In a thin provision system, each user would only take up the amount of disk space they are actually using. If the two users have each saved 10GB of data (totaling 20GB), 80GB would remain free on the disk for other users. Therefore the 100GB drive can easily accommodate three or more users, each believing they have access to 50GB of space. Essentially, the system claims to have more physical resources than are actually available. This is called “overprovisioning.”

What are the advantages of thin provisioning?

Thin provisioning uses disk space more efficiently than thick provisioning. It enables the squeezing of more users onto a particular volume of physical storage, while also avoiding excess capacity. Network administrators are then freed up from maintaining vast amounts of unused disk space. This saves funds in purchasing storage, time in maintaining it, and energy in running it. With less hardware, a thin-provisioned storage solution will take up less physical space and offer an efficient solution for the right clients.

Does thin provisioning affect performance?

A thin-provisioned disk exhibits the same performance as a lazy-zeroed thick-provisioned disk. Lazy zeroing simply means that existing data (binary ones and zeroes) is overwritten without being converted to all zeroes first. Eager zeroing, by contrast, wipes a disk clean when data is deleted (turning it to zeroes) and new data is written on this blank slate. A thick-provisioned eager-zeroing disk will write data faster than a thin-provisioned disk.

Because of overprovisioning, thin provisioning will cause problems when users approach their maximum storage capacity. It’s useful to compare disk provisioning methods to banks. A “thick-provisioned” bank would keep sufficient cash on hand to cover all its deposit accounts. Yet most banks instead choose to operate as “thin provisioned” storage disks would, with only a portion of the cash on hand. When too many depositors seek to withdraw their funds at once, the cash is exhausted, causing a run on the bank. The same issue can occur with thin provisioning. If users seek to write more data than there is physical storage space, the drive will max out and they’ll be unable to save anything. Therefore it’s absolutely crucial that system administrators continuously monitor storage use, adding new capacity when needed.

MSPs need to carefully consider the difference between thick and thin provisioning when deciding what type of storage will best meet their clients’ needs.

Read through our blog for more articles to help you more effectively manage your networks.