[CentOS] C7: How to configure raid at install time

Thu Nov 19 22:49:37 UTC 2015
Devin Reade <gdr at gno.org>

--On Thursday, November 19, 2015 11:54:19 AM -0700 Warren Young 
<wyml at etr-usa.com> wrote:

> ?Twas *progress* that made it so, specifically the fact
> that even a throwaway USB key has enough space to hold the complete OS on
> it these days.

For the record, size of the disk was never the original motivation for
keeping / separate, at least within my memory; it was to minimize the
amount of disk space that needed to be fsck'd before bringing the system
to single user mode without needing to revert to "rescue media" (at
that time, the 125MB tape on which the OS was shipped). Even in the days of
SunOS 3 (that's SunOS, not Solaris) I was installing the entire OS on
one physical drive, partitioned.  Sure, NFS and USENET servers had many
drives, but most machines were single drives.

Beyond that, I don't really want to get into a flame war on stuff
that has been hashed through before.

The main message is that while CentOS 6 and before *could* have
/ and /usr on different filesystems, don't do it with CentOS 7
per <https://access.redhat.com/solutions/53005> (paywalled).
TL;DR: you'll have trouble booting some configurations including
those using iSCSI.