[TriLUG] SL (RHEL) 7 installed on software-RAID1 (mirrored) drives

[David Burton]

Thanks for the reply, Dwain.

There's no hardware RAID support in this laptop. I'm just using regular
Linux software RAID1 (mirrored drives).

Both drives are spinning-platter HDDs, with exactly the same number of LBA
sectors.

I googled, and based on what I found I tried an experiment. At the boot
menu I pressed "e" to edit the kernel boot parameters, and changed "rhgb
quiet" to "bootdegraded=true" and then booted. That let me see more status
messages flying by, but it didn't enable the machine to boot normally when
a drive was missing. It still stopped at the same  "Welcome to emergency
mode" screen.

The following was was what I saw with the Seagate drive removed, and the
WDC drive remaining. The last few lines look like the following (except
that "...." denotes where I got tired of typing):

*[  OK  ] Started Activation of DM RAID sets.*
*[  OK  ] Reached target Encrypted Volumes.*
*[  14.855860] md: bind<sda2>*
*[  OK  ] Found device WDC_WD1600BEVT-00A23T0.*
         Activating swap /dev/disk/by-uuid/add41844....
*[  15.190432] Adding 3144700k swap on /dev/sda3.  Priority:-1 extents:1
across:3144700k FS*
[  OK  ] Activated swap /dev/disk/by-uuid/add41844....
[ TIME ] Timed out waiting for device dev-disk-by\x2duuid-a65962d\x2dbf07
....
*[DEPEND] Dependency failed for /safe.*
*[DEPEND] Dependency failed for Local File Systems.*

*[DEPEND] Dependency failed for Mark the need to relabel after reboot.*

*[DEPEND] Dependency failed for Relabel all file systems, if necessary.*
*[  99.299068] systemd-journald[452]: Received request to flush runtime
journal from PID 1*

*[  99.3298059] type=1305 audit(1415512815.286:4): audit_pid=588 old=0
auid=4294967295 ses=4294967295 subj=system_u:system_r:auditd_t:s0 res=1*
*Welcome to emergency mode! After logging in, type "journalctl -xb" to view*
*system logs, "systemctl reboot" to reboot, "systemctl default" to try
again*
*to boot into default mode.*
*Give root password for maintenance*
*(or type Control-D to continue):*


Any other ideas?

Dave



On Sat, Nov 8, 2014 at 7:09 PM, Dwain Sims <dsims at bayleafnc.org> wrote:

>
>
> *Comments below Dwain*
>
>
> ---------- Forwarded message ----------
> From: David Burton <ncdave4life at gmail.com>
> To: Triangle Linux Users Group General Discussion <trilug at trilug.org>
> Cc:
> Date: Sat, 8 Nov 2014 03:21:17 -0500
> Subject: [TriLUG] SL (RHEL) 7 installed on software-RAID1 (mirrored) drives
>


> I decided to set up a new server. I started with an AMD Turion X2 based
> laptop with two SATA drive bays. (It used to have Windows Vista on it.) I
> installed a pair of 160GB blank drives in the two bays (one Seagate and one
> WDC),
>
>
>
>
>
>
>
>
> *Are spinning disks or SSD?  I would be somewhat suspicious that you have
> slightly different drive geometry since they are not identical (either
> way). Are you using a RAID controller?  Or is there RAID built on to this
> motherboard? Or is this some sort of software RAID (it does not sound like
> it from your description).*
>
>  and set out to install Scientific Linux 7.0 on a RAID 1 (mirrored)
> configuration.
>
> The first hiccup was that the installer was apparently incapable of setting
> up the two drives for RAID1.
>
>
> *If it is hardware RAID of some sort, I would not expect the installer to
> set that up for you.  Likely from the BIOS or a separate utility.*
>
> So I booted from a PartedMagic CD, and used it to do the partitioning, and
> created the RAID1 array.
>
>
> *That sounds more like software RAID, though?  Is this LVM doing the
> mirroring?*
>
>  (I partitioned the two drives identically,
> reserving 3GB on each drive for a Linux Swap partition.) Then I booted the
> SL DVD, and tried the install again. It recognized the RAID1 array,
> formatted it for ext4, and installed smoothly (though I did a lot of
> guessing on the "Software Selection" screen).
>
> At this point, the machine seemed okay. I shut it down, started it again,
> and it was fine.
>
> So far so good. So then I tested the RAID1 functionality: I shut down the
> computer, removed one of the drives, and tried to boot it.
>
> I was expecting it to display some error messages about the RAID array
> being degraded, and then come up to the normal login screen. But it didn't
> work. Instead I got:
>
> Welcome to emergency mode! After logging in, type "journalctl -xb" to view
> system logs, "systemctl reboot" to reboot, "systemctl default" to try again
> to boot into default mode.
> Give root password for maintenance
> (or type Control-D to continue):
>
> The same thing happens regardless of which drive is missing.
>
> That's no good! The purpose of the mirrored drives is to ensure that the
> server will keep on running of one of the drives fails.
>
> Ctrl-D just gets me back to a repeat of the same "Welcome to emergency
> mode" screen. So does entering my root password and then "systemctl
> default".
>
> Does anyone have any suggestions for how to make this thing boot & run
> "normally" (with a degraded RAID1 array) when a drive fails?
>
> As it stands, it appears that installing on RAID1 mirrored drives will just
> double the chance of a drive failure bringing down the server. That is
> *not*
> what I was hoping to achieve w/ mirrored drives.
>
> Two other notes:
>
> 1. I'm seeing some apparently-innocuous errors:
>   ATA*x*: softreset failed (device not ready)
> The "*x*" depends on which drives are installed. I get more of those
> errors
> with two drives installed than with only one.
>
> 2. At the "Software Selection" screen I didn't know what to pick, so I
> chose:
> "General Purpose System" +
>   FTP Server
>   File and Storage Server
>   Office Suite and Productivity
>   Virtualization Hypervisor
>   Virtualization Tools
>   Development Tools
>
> *Should make no difference.*
>