The storage trilemma: Speed vs Size vs Costs

When crafting your ideal personal computing setup, a few key elements take center stage; among them, "speed" reigns supreme. In today's landscape of diverse computing systems and devices, the CPU's capabilities are nearly maxed out, and expanding memory has become a cost-effective option. However, with these robust systems comes a significant responsibility, and that's where storage enters the picture. In this blog, we'll delve into the crucial role of storage in optimizing your computing experience. 

Evolution of data storage: From SATA to SAS, transforming datacenter performance 

In most cases, your home desktop device will still have a hard disk attached to a SATA connection. SATA stands for Serial Advanced Technology Attachment, being the successor of the older IDE storage interface for your home computer. It has, despite being serial over parallel, better throughput performance than the older disk connections, which was needed to keep up with the ever-changing revolution of storage devices (disks).  

In the sight of cloud providers this is more complex. With the introduction of virtualization in datacenters, the need for more and bigger storage became inevitable. The range of ‘enterprise’ storages had been occupied mostly by SCSI devices, with which one could connect (daisy chain) 7 different storages to one controller. This has been the basis for the SAS (Serial Attached SCSI) interface, where 127 devices could be connected to a single controller. This, and the disk devices getting bigger and bigger, caused the SAS drive arrays to become the de facto standard on datacenter (virtualization) storage for many years to come. Having a standard HDD (or spinning disk) connected to the SAS-bus interface would triple the speed of a regular SATA interface.  

Need for Speed: SSD revolution and the rise of NVME

The next game-changer in this roadmap was the introduction of SSDs or Solid-State disks. Where the (up until then) conventional disks had a bunch of spinning magnetic disks to hold the data, the speed of reading and writing was defined by the speed with which the plates were revolving. So, a 10.000 RPM disk would be faster than a disk that did 5400 RPM or even 7200 RPM. However, this moving part would still be the blocking element in the overall chain and would never saturate the SATA or SAS path. With an SSD device, there are no spinning items and, with all data stored in memory, having access times far below any hard disk would be able to achieve.   

At this point, not the storage device itself but the interface became a bottleneck in the race to maximize the speed. With SAS still able to keep a good pace with the speed, having more significant and faster SSD storage would quickly saturate the interface.   

In the meantime, the SSD had already been removed from its regular 2.5" form factor (the 'laptop' size) and put on a small, easy-to-install board. With this new look, a new name, Non-Volatile Memory Express, or NVME, was introduced. In the early days of its existence, this proved to be nothing more than a name change because the widely used M.2 NVME disks just used a SATA interface, so this would turn out no different than the 'regular' SSD storages.  

The role of next-gen interfaces and data efficiency

To fully extend the use of SSD (in any form factor), a new interface should be used to increase the complete system's throughput capabilities and remove the interface speed bottleneck. For devices other than storage, like graphics cards, a new interface type was introduced, the Peripheral Component Interconnect (Express) interface, or PCI-e for short. This interface exceeded the speed of SAS many times and used data lanes to separate individual transfers (reads or writes). In the newest GEN5 NVME SSD storages, up to 16 routes are possible. Because the speed of the data throughput has increased significantly, the NVME storage needs unique data optimization technology to make it a reliable repository, thus making it a lot more expensive.     

For many data center installations, storage must comply with several critical elements, such as:  

• Fast  
• Expandable  
• Reliable  
• Easy to maintain
• Economical 

Affordable & reliable storage solutions at Tilaa  

The economical element is, especially for you as a customer, dependent on the others. In short, all storage comes with a price.  

As a cloud provider, Tilaa addresses the storage questions with the customer in mind. It must be reliable and affordable, with a speed to go with it and which does not cause any blocking issues for you as a customer.   

At this time, the amount of storage in use is such that installing NVME on PCI-e interfaces would be a massive investment without noticeable advantages. Even if the disks and interfaces are changed, the storage would still be as ‘fast’ as it is now because most of it is attached via the network. Moreover, with SAS-attached SSDs, the current configuration is easier to maintain and expand. In most cases, changing an SSD-disk can be done via a hot swap, whereas with NVME, the node has to be brought down and thus taken out of service. Also, compared to SAS, the PCI-e bus is limited in the number of devices attached to the bus. 

The good news with this is that Tilaa is constantly working on optimizing the whole infrastructure, including the introduction of multi-tier storages (of various speeds) and introducing new storage principles like object storage or network attached block storages.