Features/SSDcache

Feature Name SSDcache

Summary

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

Owner

• Name: Rolf Fokkens
• Email: rolf@rolffokkens.nl

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.

Scope

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)

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.

Dependencies

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.

Documentation

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

Here are some links to dm-cache and bcache

Comments and Discussion

• See Talk:Features/SSDcache