[PLUG] Question About RAID and LVM - Ubunu 14.04

Mark Phillips mark at phillipsmarketing.biz
Fri Sep 19 01:17:28 UTC 2014


Josiah,

Thanks for your response. It looks as if LVM is using the hardware directly
-

mark at tsunami:~$ sudo pvscan -v
[sudo] password for mark:
    Wiping cache of LVM-capable devices
    Wiping internal VG cache
    Walking through all physical volumes
  PV /dev/sda1   VG vg1_tsunami   lvm2 [931.51 GiB / 0    free]
  PV /dev/sdb1   VG vg1_tsunami   lvm2 [931.51 GiB / 0    free]
  Total: 2 [1.82 TiB] / in use: 2 [1.82 TiB] / in no VG: 0 [0   ]
mark at tsunami:~$

Part of my confusion is that mdadm is NOT installed on my system.
Everything I have read about raid involves mdadam, but as I said in my
original post, it is not installed -
mark at tsunami:~$ sudo mdadm
sudo: mdadm: command not found
mark at tsunami:~$

However, in the Ubuntu 14.04 server installer I specifically set up the
drives to be in a raid1 array. From the instructions I followed (see
reference above)

   - Designate your new partition for RAID by selecting “Physical volume
   for RAID” at the “How to use this partition:” prompt. This process will
   create a new RAID device.
   Repeat the previous step for the other physical disk.
   - Here’s the overview of my partition layout and settings: (mine looked
   the same, but the drives are 1 TB Samsung drives.

   -

   At the prompt asking, “Write the changes to disks and configure LVM?”
   Select yes.

I then entered the LVM process, finished the installation, picked a few
packages including ubuntu-desktop, and as I said above it boots just fine.

What should I do now?

I could do a re-install, but the steps won't change, so I am not confident
I will get a RAID1 array out of it.

Or, I could install mdadm and see what it says.....but can a software raid
be installed without mdadm? If the system is magically configured as a raid
array, will installing mdadm screw it up?

I don't believe this laptop has any raid hardware installed....at least
System76 never told me about it, and I asked them to configure the drives
as RAID1 when I bought the beast and they said they could not do that.

Thanks,

Mark

On Thu, Sep 18, 2014 at 3:45 PM, Josiah Luscher <sy at josiahluscher.com>
wrote:

> Finally a question I might be able to help with!  I'm so excited!  I can
> think of many ways to get more information to help alleviate the
> confusion.  I'd suggest starting with an LVM scan of physical volumes:
>  "pvscan -v".   That will tell you weather LVM is using 'md#'  devices, or
> the hardware directly ('sd#' devices).   You could also query the hard
> drives with mdadm for RAID headers.  I think the command would be " mdadm
> --query /dev/sd#.
>
>
> On September 18, 2014 1:28:23 PM PDT, Mark Phillips <
> mark at phillipsmarketing.biz> wrote:
> >I am confused about a RAID1 and LVM installation using Ubuntu 14.04
> >server.
> >I have a new System 76 Gazelle Pro laptop with two 1 TB SSD drives. I
> >re-installed the system using the server version of 14.04 so I could
> >have
> >the installer create the raid and lvm. I followed this blog post -
> >http://blog.miketoscano.com/?p=307, and the steps in the installer to
> >create the raid and then the lvm, and then install the OS, and it all
> >seemed to work. I then installed the ubuntu-desktop and then the
> >system76
> >drivers. It all seems to be working.
> >
> >However, I cannot find mdadm. It does not appear to be installed. I
> >looked
> >at /etc/fstab and I see
> >mark at tsunami:~$ cat /etc/fstab
> ># /etc/fstab: static file system information.
> >#
> ># Use 'blkid' to print the universally unique identifier for a
> ># device; this may be used with UUID= as a more robust way to name
> >devices
> ># that works even if disks are added and removed. See fstab(5).
> >#
> ># <file system> <mount point> <type> <options> <dump> <pass>
> >/dev/mapper/vg1_tsunami-root / ext4 errors=remount-ro 0 1
> >/dev/mapper/vg1_tsunami-swap none swap sw 0 0
> >
> >And the free space shows
> >mark at tsunami:~$ df -h
> >df: ‘/run/user/107/gvfs’: Permission denied
> >Filesystem Size Used Avail Use% Mounted on
> >/dev/mapper/vg1_tsunami-root 1.8T 120G 1.6T 7% /
> >none 4.0K 0 4.0K 0% /sys/fs/cgroup
> >udev 7.8G 4.0K 7.8G 1% /dev
> >tmpfs 1.6G 1.2M 1.6G 1% /run
> >none 5.0M 0 5.0M 0% /run/lock
> >none 7.8G 144K 7.8G 1% /run/shm
> >none 100M 40K 100M 1% /run/user
> >
> >There is no mdadm.conf.
> >]mark at tsunami:~$ sudo locate mdadm
> >[sudo] password for mark:
> >/usr/share/bash-completion/completions/mdadm
> >
> >And mdstat does not seem correct from what I have read.
> >]mark at tsunami:~$ cat /proc/mdstat
> >Personalities :
> >unused devices: <none>
> >
> >Am I missing something? Do I really have what I intended to install? I
> >don't want to pull all my files over to the machine until I am sure it
> >is
> >working as intended.
> >
> >Thanks,
> >
> >Mark
> >_______________________________________________
> >PLUG mailing list
> >PLUG at lists.pdxlinux.org
> >http://lists.pdxlinux.org/mailman/listinfo/plug
>
> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
> _______________________________________________
> PLUG mailing list
> PLUG at lists.pdxlinux.org
> http://lists.pdxlinux.org/mailman/listinfo/plug
>



More information about the PLUG mailing list