Changes/SSD cache

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== How To Test ==
 
== How To Test ==
<!-- This does not need to be a full-fledged document. Describe the dimensions of tests that this change implementation is expected to pass when it is done.  If it needs to be tested with different hardware or software configurations, indicate them.  The more specific you can be, the better the community testing can be.
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Implementing a caching root FS requires a reinstall for sure, because caching cannot be added to existing volumes!
  
Remember that you are writing this how to for interested testers to use to check out your change implementation - documenting what you do for testing is OK, but it's much better to document what *I* can do to test your change.
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Testing involves doing a clean install of Fedora, while configuring in anaconda a cached root FS. After the installation the cache state should be checked (if it is operational or not.
  
A good "how to test" should answer these four questions:
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Additional tests:
 
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* run benchmarks (see performance improvement over non cached storage)
0. What special hardware / data / etc. is needed (if any)?
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* update the kernel (see if dracut builds a functional initramfs including caching
1. How do I prepare my system to test this change? What packages
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* ...
need to be installed, config files edited, etc.?
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2. What specific actions do I perform to check that the change is
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working like it's supposed to?
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3. What are the expected results of those actions?
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<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
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N/A (not a System Wide Change)
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== User Experience ==
 
== User Experience ==

Revision as of 21:40, 8 July 2013

Contents

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
  • Release notes owner:

Current status

  • Targeted release: Fedora 20
  • Last updated: 2013-06-25
  • Tracker bug: <will be assigned by the Wrangler>

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

Scope

  • Proposal owners: Enable caching features in new kernels
  • Other developers: Support the caching features in their respective packages. Special focus should be on making the system boot from a cached root FS.
  • Release engineering: All packages should operate in close harmony te make this work. Only a rebuild of the relevant packages is required.
  • Policies and guidelines: No changes I think.

Upgrade/compatibility impact

N/A (not a System Wide Change)

How To Test

Implementing a caching root FS requires a reinstall for sure, because caching cannot be added to existing volumes!

Testing involves doing a clean install of Fedora, while configuring in anaconda a cached root FS. After the installation the cache state should be checked (if it is operational or not.

Additional tests:

  • run benchmarks (see performance improvement over non cached storage)
  • update the kernel (see if dracut builds a functional initramfs including caching
  • ...

User Experience

N/A (not a System Wide Change)

Dependencies

N/A (not a System Wide Change)

Contingency Plan

  • Contingency mechanism: (What to do? Who will do it?) N/A (not a System Wide Change)
  • Contingency deadline: N/A (not a System Wide Change)
  • Blocks release? N/A (not a System Wide Change), Yes/No

Documentation

N/A (not a System Wide Change)

Release Notes