Speeding up slow disks with SSD caching
Afterburner
Flash memory is fast but also expensive. Caching with Flash provides a way out: A smaller and cheaper SSD can speed up the disk.
Hard disks are inexpensive, and they have huge capacities, but they are also slow. Solid state disks (SSDs) are fast, but smaller and more expensive. If you combine the advantages of a hard disk with an SSD-based cache, you pick up a large performance gain at a reasonable cost.
An application generally does not want all the data at once; most of the data is in the state of being ignored most of the time. Caching lets you move the most frequently requested data to an exclusive, fast medium and leave the less-frequently accessed data on the cheaper but slower background medium.
The Linux environment has several tools that provide the necessary software to support hard-disk caching. Does it help to use an SSD-based flash drive as a cache for a traditional hard disk? We decided to find out. This article explores the possibilities for caching with the Linux caching tools Enhance IO and dm-cache. If you are new to the topic of caching, and you would like some additional information on choices you might have to make, see the boxes titled "A Little Cache Theory" and "How Flash Works."
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
The Bullet-Proof KDE Software Initiative Is Coming
KDE, Techpaladin, and Kubuntu Focus have announced a new initiative that will provide at least three years of support for KDE Plasma 6.6 LTS and related software.
-
Linux Mint Shares a Possible Kernel Cleanup Solution
For those on Linux Mint who like to keep multiple kernels around but don't want them to take up too much space, you might be getting a new automated tool.
-
CachyOS Gets an Update
CachyOS August 2026 release is now available with the latest version of KDE, some new features, and plenty of improvements.
-
The Linux Kernel Dev Staging Area Now Rejects AI-Generated Patches
Unless a kernel patch is a valid security fix, it will be rejected if it was created using AI.
-
Linux Surpasses Double-Digit Market Share
According to two sources, the Linux operating system has hit a major milestone in market share that naysayers thought would never happen.
-
AI Helped Develop a Linux Exploit
A use-after-free race exploit was discovered and exploited on CentOS Stream 9.
-
Yet Another Linux Kernel Vulnerability Discovered
Affecting millions of systems, a kernel flaw discovered by Qualys could allow users to gain root privileges.
-
Ubuntu 26.10 to Include Ubuntu Certified Hardware Check
If you've ever wondered if your laptop or PC is officially certified to run Ubuntu, that curiosity will soon be met.
-
Substantial Update to IPFire Now Available
The lastest version of IPFire features a fundamental change to how the system handles DNS.
-
Gnome Working on Test Center App to Make Testing Easier
It's now possible to test experimental features on the Gnome desktop without worrying that you'll break things.