F21 Self Contained Change: LVM Cache Logical Volumes

[Jaroslav Reznik]

= Proposed Self Contained Change: LVM Cache Logical Volumes = 
https://fedoraproject.org/wiki/Changes/Cache_Logical_Volumes

Change owner(s):  Alasdair G. Kergon <agk at redhat.com>, David Cantrell 
<dcantrel at redhat.com>, Dave Lehman <dlehman at fedoraproject.org>

LVM can now use fast block devices (e.g. SSDs and PCIe Flash) to improve the 
performance of larger but slower block devices. These hierarchical or layered 
logical volumes are called Cache Logical Volumes in LVM. 

== Detailed Description ==
LVM is now capable of using fast block devices (e.g. SSDs) as write-back or 
write-though caches for larger slower block devices. Users can create cache 
logical volumes to improve the performance of their existing logical volumes 
or create new cache logical volumes composed of a small and fast device 
coupled with a large and slow device. These cache logical volumes can be used 
with most LVM segment types, including RAID 1/4/5/6/10, linear, stripe and 
thin pools. 

== Scope ==
* Proposal owners:
The LVM team must deliver the lvm2 package implementing cache LV (already 
included in release 2.02.106)

* Other developers: N/A (not a System Wide Change) 
The Anaconda team must develop a UI for configuring cache LVs during 
installation.  If Anaconda support is not provided, users will have to 
configure cache LVs after installation or by dropping into a command line.  
Also, Anaconda could fail if installing a new OS onto an existing cache LV if 
support is not provided. 

Anaconda team signed as co-owners of this Change.

The dracut team must provide boot support.  If dracut does not provide 
support, cache LVs will not be usable as root devices.

* Release engineering: N/A (not a System Wide Change) 
* Policies and guidelines: N/A (not a System Wide Change)