Summary

Karmic should fully embrace Solid State Disk (SSD) storage in two ways: to ensure the SSD flash wear is minimised and to maximise SSD I/O performance.

AIM: Maximise benefits of fast speed of SSD, and reduce wear.

This can be achieved by:

Release Note

This section should include a paragraph describing the end-user impact of this change. It is meant to be included in the release notes of the first release in which it is implemented. (Not all of these will actually be included in the release notes, at the release manager's discretion; but writing them is a useful exercise.)

It is mandatory.

<Not yet complete>

Rationale

SSD storage is becoming more common on laptops and netbooks as cost reduces and capacity increases. SSD offers benefits in increased I/O performance (for example reduced read/write/seek times) hence quicker boot times, however, filesystem and tuning choices are required to reduce flash wear over extended periods of use.

The ATA TRIM command will soon be supported in newer SSDs and if kernel permits, should be used to reduce wear and increase performance when deleting blocks.

User stories

Assumptions

Implementation: Use Appropriate Log Structured File Systems

Linux provides several log structure file systems, namely:

While it is up to the user to choice the appropriate file system for their work load, it would be helpful if the user could be recommended log based (journalling) file systems that are appropriate for the SSD.

The main issue is which file system is most appropriate. At present there is a choice from:

ext4, reiserfs, jfs, xfs, btfs to name a few. Note that btfs has copy-on-write capability, which should show some form of performance improvement and reduce flash wear. Will it be stable for Karmic?

Requires some benchmarking to determine which is the winner in terms of speed vs flash wear, however ext4 seems to be a good choice, and will be default for Karmic. Benchmarking needs to be done against some typical usecases:

Implementation: Tune filesystems

Partition Alignment:

I/O schedulers:

Mount options:

Recommendations

Code Changes

Migration

Test/Demo Plan

BoF agenda and discussion

Use this section to take notes during the BoF; if you keep it in the approved spec, use it for summarising what was discussed and note any options that were rejected.


CategorySpec

KernelTeam/Specs/KarmicSSD (last edited 2009-08-11 20:15:50 by linardv)