[CentOS] CentOS 7: software RAID 5 array with 4 disks and no spares?

[Chris Murphy]

On Wed, Feb 18, 2015 at 3:59 PM, Niki Kovacs <info at microlinux.fr> wrote:
> Well, maybe it's just me. I've started Linux on Slackware 7.1 and used
> pretty much every major and minor distribution under the sun. I know my way
> around Slackware, Debian, CentOS, FreeBSD, Gentoo, Arch and many more, and
> my favourite installer is - and will always be - Slackware's bone-headed
> NCurses installer that lets the admin do pretty much what he wants - and
> needs - to do.

I'm definitely not suggesting it's just you. I'm coming up with a
plausible explanation for the confusion, and that's a misalignment
between your expectations and the installer's presentation. I can tell
you, having using this installer since Fedora 18, it has changed
immensely from the initial versions.

My personal view on installers is extremely biased toward the user
staying out of trouble, they shouldn't have to read documentation for
a GUI installer. The entire point of a GUI installer is to protect the
user from bad choices, non-standard or unsupportable choices, or
having to read a volume of documentation, or become an expert for
something that quite frankly happens rarely: OS installation.

And my very strong bias is affected by both the OS X and Windows
installers, which are completely, utterly, brain dead. And I mean that
in a good way. It's impossible for the user to get confused, there are
almost no choices. It's next to impossible for there to be bugs, there
are almost no choices. Every outcome of the installation is
supportable, because the user wasn't allowed to create completely
nutty layouts that make no sense.

Now, for various reasons Anaconda (the Fedora/RHEL/CentOS installer)
is exceptionally more capable than almost any other GUI installer out
there. And that makes it complex, prone to bugs, and prone to
confusing users and subject to criticism. That's just the inevitable
result of trying to do so many things.



> I love CentOS, been using it since 4.x. But frankly, CentOS 7's installer is
> an abomination.

Having done many hundreds, possibly over a thousand installations with
it, I'm well aware of how confusing it can be. So the criticism is
almost certainly reasonable, no matter what. I'm just saying that once
you understand the point of view of the installer (which arguably you
should not have to do), things become much easier. That doesn't mean
easy. Just easier.


> All's well that ends well. It only took me a day and a half to figure out
> how to configure RAID 5 using the graphical assistant. Something I could
> have done in less than three minutes using fdisk and mdadm --create.

Right, but inevitably that failure is the result of misalignment of
expectations between you and the installer. That's an explanation, not
an assignment of blame. The reason why working directly with
partitions is easy for you, and what you expect, is simply because
that's how you've always done it, since  that's how all other
installers behave. Anaconda is really the first installer that
deemphasizes that. And I think that's a bold move, and for a GUI
installer that's necessarily taking on a lot of complexity I think
it's probably a good idea overall. But it does have a lot of bugs
still... it's definitely doing things that I don't like.

But any experienced sysadmin knows how users say "it should work like
X" and how often they're wrong. They're just used to things that work
like X and that's why they want this new problem to work that same
way. So as a sysadmin or network engineer you ask questions to find
out how to get the user from A to B, and the details of "how it should
work" are your domain, your specialty, and ultimately they don't
really care how it happens, they just want to get to B. And once
that's well understood, you can get on with things.

And one problem is the installer can't really have that kind of
diplomatic conversation about what its worldview is, so that the user
expectations re-align with the end goal in mind, not how to get there.

-- 
Chris Murphy