[PLUG] Question About RAID and LVM - Ubunu 14.04

Fri Sep 19 04:05:36 UTC 2014

Loren,

Thanks for you comments.  As I said in my first post, I used ubuntu server
to install both raid and lvm, and then installed ubuntu-desktop. The image
in my second post is from the text based ubuntu server installation process.

I guess I could try it again, but I don't see how anything would change.

Thanks,

Mark
On Sep 18, 2014 8:54 PM, "Loren M. Lang" <lorenl at north-winds.org> wrote:

> On Thu, 18 Sep 2014 18:17:28 -0700, Mark Phillips
> <mark at phillipsmarketing.biz> wrote:
> > Josiah,
> >
> > Thanks for your response. It looks as if LVM is using the hardware
> directly
>
> Yes, it looks like LVM is directly using the hardware indeed. The
> Ubuntu Desktop installer does not include RAID support nor install mdadm
> by default. You can get mdadm by doing sudo apt-get install mdadm from
> the command-line. In fact, Ubuntu would have said so if you tried
> running mdadm without using sudo. It's not smart enough, though, to
> recommend such things via sudo.
>
> The real problem is that both hard drives are allocated as independent
> physical volumes to LVM giving you twice the space you would normally
> have. I also noticed that you have all of the volume group entirely
> allocated to one physical volume. That kind of negates any benefit to
> using LVM as live volumes can't be shrunk. Most benefits of LVM like
> taking live snapshots or creating new volumes on the fly require that
> there is some unallocated space in the volume group. There is a way to
> restore RAID without reinstalling, but it's a long, complicated
> procedure.
>
> I recommend to reinstall and use the Ubuntu Server ISO. Set up RAID and
> LVM as you see fit. Once Server is finished installing, just install the
> ubuntu-desktop package (or kubuntu-desktop, xubuntu-desktop, etc.) and
> you will have a normal desktop. Ubuntu Desktop is actually based on the
> standard Server install plus everything ubuntu-desktop pulls in.
>
> sudo apt-get install ubuntu-desktop
>
>
> > -
> >
> > 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
> >> >_______________________________________________
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> >> >http://lists.pdxlinux.org/mailman/listinfo/plug
> >>
> >> --
> >> Sent from my Android device with K-9 Mail. Please excuse my brevity.
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