LVMthinp (was: default file system - Comparison to Workstation TS)

[Chris Murphy]

Server Technical Specification Working Session
http://meetbot.fedoraproject.org/fedora-meeting-1/2014-02-27/fedora-meeti...

>  16:06:36 <sgallagh> simo: To answer your question about
> overcommit: that is *possible*, but we can be smarter about it in the default partitioning
Anaconda currently disallows overcommitting.

>  15:48:19 <mitr> (Again, having a per-directory instead of
> per-user quotas would be rather beneficial here) 
A related item that came up is quotas. XFS supports project quotas. So that's possible
in the case where you're on the fence if something should have a separate LV. Project
quotas were just proposed as an ext4 feature last month.

My two small concerns about LVM thinp by default: 

1. XFS is highly parallel + the parallel writes is a trigger for the current thinp
fragmentation issue. So it's a "good" combination to reveal this problem. 

2. There is an outstanding bug between XFS and LVMthinp that I think the LVM folks might
need to be pinged on. The wrong number of XFS AG's is being assigned to virtual size
LVs and this will reduce performance.

https://bugzilla.redhat.com/show_bug.cgi?id=1003227


Chris Murphy