Re: [atomic-devel] Changing partitioning defaults discussion

[Colin Walters <walters verbum org>]

On Mon, Jun 5, 2017, at 03:12 PM, Dusty Mabe wrote:
> 
> - Why not stick with the distro default? 

Well, what is "distro default"?  This is a messy topic; some things
*are* defaults in blivet, and apparently the default filesystem is ext4,
but for Fedora Server it's overridden.  I'm honestly not sure a lot
of serious thought is put into those blivet defaults, it seems to me
to be a lot more like inertia.

I've attached an updated patch which links to the Server thread.
For us, the argument that it's the RHEL default also carries weight,
but for containers, it's what we test with the most downstream.  

A good specific technical advantage XFS has over ext4 for this
use case (with overlayfs) is that inodes are dynamic, and when
you're doing containers you simply tend to have more filesystem
trees.

> - If we have a good reason can we do this in a different commit with a 
>   commit message that is relevant?

I updated the existing commit message, I think the "match Fedora Server"
rationale should cover it, right?

From 430a8722acd55c93d8794e93c54c992e2c8a7ee7 Mon Sep 17 00:00:00 2001
From: Colin Walters <walters verbum org>
Date: Mon, 5 Jun 2017 12:46:40 -0400
Subject: [PATCH] Match Fedora Server's partitioning

The max size of 3GB is pretty restrictive for most bare metal installs where we
expect peopl to have at least one large physical drive.  This gives
a lot more headroom for things that may be stored in `/` like e.g. the systemd
journal.

The max size of `15GB` ensures that if the user wants to make other LVs, there's
enough space in the VG to do so.

Note this deletes the `/boot` override; while I don't like the new Blivet
default of `1G`, it's a messy topic, and I don't think it's worth carrying
an override in the baremetal path just for that.

Note we also explicitly start matching the Fedora Server default of XFS,
with the same rationale; there's a [long thread](https://lists.fedoraproject.org/archives/list/server lists fedoraproject org/thread/W4KWEEKADZDCAFK4XJYEJG34DZLTC3BB/)

For AH, we've been using XFS by default, this just ensures it's used
across all filesystems by default.

One specific reason why XFS is good over ext4 is support for dynamic inodes is
really quite nice when using `overlayfs` and containers.
---
 installclass_atomic.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/installclass_atomic.py b/installclass_atomic.py
index cce1470..c3677ca 100644
--- a/installclass_atomic.py
+++ b/installclass_atomic.py
@@ -36,11 +36,13 @@ class AtomicInstallClass(FedoraBaseInstallClass):
     name = "Atomic Host"
     sortPriority = 11000
     hidden = False
+    defaultFS = "xfs"
 
+    # This is intended right now to match Fedora Server; if changing this,
+    # please discuss on https://lists.projectatomic.io/projectatomic-archives/atomic-devel/
     def setDefaultPartitioning(self, storage):
-        # 3GB is obviously arbitrary, but we have to pick some default.
         autorequests = [PartSpec(mountpoint="/", fstype=storage.default_fstype,
-                                size=Size("1GiB"), max_size=Size("3GiB"),
+                                size=Size("3GiB"), max_size=Size("15GiB"),
                                 grow=True, lv=True)]
 
         bootreqs = platform.set_default_partitioning()
@@ -56,7 +58,6 @@ class AtomicInstallClass(FedoraBaseInstallClass):
             if autoreq.fstype is None:
                 if autoreq.mountpoint == "/boot":
                     autoreq.fstype = storage.default_boot_fstype
-                    autoreq.size = Size("300MiB")
                 else:
                     autoreq.fstype = storage.default_fstype
 
-- 
2.9.4