From Fedora Project Wiki

Feature Name SSD cache


Using recent kernel (3.9 and later) features for (fast) SSD caching of (slow) ordinary hard disks.


Current status

  • Targeted release: Fedora 20
  • Last updated: 20130523
  • Percentage of completion: 0%

Detailed Description

Recent Linux kernels support the use of Solid State Drives as caches for rotational hard disks. Because the high cost per GB for SSD devices this feature may bring the best of both: fast end big yet affordable storage capacity. Linux kernel 3.9 introduced dm-cache, kernel 3.10 introduces bcache.

Benefit to Fedora

In general operating systems increasingly (will) support SSD caching, because of it's value to users: an affordable solution for both fast and large storage.


Several tools are in scope:

  • Dracut (to support SSD caching for root FS)
  • Anaconda (to support SSD caching in clean installs)
  • bcache-tools (a new package to support bcache)
  • udev (for auto detection of bcache devices)

How To Test

User Experience

Users will experience improved disk performance without explicitly having to decide what to store an fast and what to store on slow media.


This feature relies on the packages as mentioned below:

Component Details
anaconda cache handling during install is needed
dracut cache handling during boot is needed
bcache-tools software can be downloaded here and here
kernel Some background info
udev integration in udev

Contingency Plan

None necessary, revert to previous release behaviour.


The feature is very new, some documentation is in the kernel sources.

Here are some links to dm-cache and bcache

Release Notes

Comments and Discussion