IBM GPFS / Spectrum Scale Alternative and Comparison

3 min readJul 6, 2022


The cloud has changed the user’s expectations for enterprise storage: Today, users expect instant provisioning of new storage, “unlimited” scalability, 24/7 uptime, and storage that can handle a wide variety of workloads — from traditional databases to massive scale-out workloads like machine learning or big data analytics.

Enterprise storage systems need to keep up with user expectations and business needs. They must dynamically adapt to rapidly changing business and application requirements, new workloads, and dynamic scaling when experiments turn into production workloads.

What is IBM SpectrumScale / GPFS

SpectrumScale, initially called GPFS, was developed over 25 years ago as the enterprise’s first distributed software storage solution. The primary purpose was to coordinate the concurrent access to a SAN (storage area network, see here) from many clients.

This explains the architecture of SpectrumScale: A SAN is block storage — almost like a giant hard drive. SpectrumScale’s architecture is very similar to a local file system, just distributed across machines. Reliably storing blocks of data was the task of the SAN. SpectrumScale provided the shared file system later.

Later on, SpectrumScale got support for a shared-nothing architecture where the file system layer handles the data redundancy across regular servers with local drives. However, this layer was “bolted” onto an existing architecture that had been designed for a completely different purpose. This dated architecture that wasn’t designed for shared-nothing storage is also one of the primary sources of the lack of flexibility and scalability in SpectrumScale/GPFS when compared to modern software storage competitors.

SpectrumScale vs. Quobyte: How they compare

The architecture is one of the main differentiators between Quobyte and SpectrumScale. The coordination of the block access limits the scalability of a SpectrumScale cluster. Even worse, SpectrumScale clients can hold locks as well. When clients get disconnected or crash, it causes the unavailability of portions of the file system.

In contrast, Quobyte is built on a scale-out architecture designed for shared-nothing distributed storage and doesn’t suffer from the scalability limits of block-based designs. Moreover, when Quobyte clients get disconnected, the availability of the file system is not affected at all.

In addition, Quobyte’s architecture delivers consistently high performance for throughput, random 4k IOPS, and small file workloads from the same file system.

When it comes to dynamically adapting the file system, SpectrumScale/GPFS suffers from a rather static configuration where settings like metadata-to-data ratio or block sizes have to be configured up-front and are difficult to change afterward. Hardware configurations inside a pool have to be homogeneous, making it difficult to upgrade clusters with newer hardware.

Quobyte is fully reconfigurable at runtime, down to individual block sizes and redundancy mechanisms, and setting per file. With the placement of individual files, Quobyte doesn’t require the rigid concept of pools and can work with heterogeneous hardware. Quobyte clusters can easily be expanded with newer generations of servers, different configurations, or larger drives.

Similarly, the lack of thin provisioning and oversubscription is among the top reasons why GPFS/SpectrumScale is not a good choice for storage-as-a-service offerings. Similarly, the limit to 256 volumes is too restrictive for modern service offerings or real-world Kubernetes clusters. Quobyte can handle 100,000s of thinly provisioned volumes with oversubscription, which greatly reduces the storage cost. With built-in multi-tenancy and security features, Quobyte makes it easy to offer storage as a service with automated instant volume deployment and Kubernetes clusters with the Quobyte-CSI plugin.

Another major difference between the two systems is the ease of use and complexity. SpectrumScale is known for its difficult installation and update procedures and the complexity of managing pools, rules, and clients. In contrast, Quobyte is built with simplicity in mind from the start. It’s available as a download with an automated installer (including the free edition) and can be managed completely from the UI. Since Quobyte runs in user space and avoids the complexity of dealing with extra kernel modules and potentially incompatible kernel versions that GPFS/SpectrumScale entails.

With Quobyte you can get great performance for any workload without the painful complexity of dated storage solutions. Quobyte is so easy to use and install that we offer our free edition for download, no questions asked.

Originally posted on Quobyte’s blog on June 27, 2022.




Quobyte empowers customers by providing real software storage so that they can keep up with the ever-increasing amounts of data in today’s data-driven world.