4.2: "mount /dev/mapper/data" not possible any more?

[whiterabbit]

Hi.
Today i installed a fresh proxmox-4.2 Server and wanted to copy an existing VM-backup to this machine.
It has 1 TB of capacity ... so there should be more than enough free space.

BUT: I cannot mount the lvm-data-partition any more. On our old server there was

/dev/mapper/pve--raid-data on /mnt/raid10-pve4 type ext4 (rw,relatime,data=ordered)

But now on 4.2 I've got:

mount /dev/mapper/pve-data /mnt/pve-data/
mount: wrong fs type, bad option, bad superblock on /dev/mapper/pve-data,
  missing codepage or helper program, or other error
  In some cases useful info is found in syslog - try
  dmesg | tail or so.

When I use "lsblk" there are also big differences between our Servers. On our new Server I get this:

NAME                         MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda                            8:0    0 931.5G  0 disk
├─sda1                         8:1    0  1007K  0 part
├─sda2                         8:2    0   127M  0 part
└─sda3                         8:3    0 931.4G  0 part
  ├─pve-root                 251:0    0   100G  0 lvm  /
  ├─pve-swap                 251:1    0     7G  0 lvm  [SWAP]
  ├─pve-data_tmeta           251:2    0   104M  0 lvm
  │ └─pve-data-tpool         251:4    0 808.4G  0 lvm
  │   ├─pve-data             251:5    0 808.4G  0 lvm
  │   ├─pve-vm--501--disk--1 251:6    0    32G  0 lvm
  │   ├─pve-vm--501--disk--2 251:7    0     1G  0 lvm
  │   ├─pve-vm--502--disk--1 251:8    0     5G  0 lvm
  │   ├─pve-vm--503--disk--1 251:9    0    20G  0 lvm
  │   ├─pve-vm--503--disk--2 251:10   0    50G  0 lvm
  │   └─pve-vm--506--disk--1 251:12   0    22G  0 lvm
  └─pve-data_tdata           251:3    0 808.4G  0 lvm
    └─pve-data-tpool         251:4    0 808.4G  0 lvm
      ├─pve-data             251:5    0 808.4G  0 lvm
      ├─pve-vm--501--disk--1 251:6    0    32G  0 lvm
      ├─pve-vm--501--disk--2 251:7    0     1G  0 lvm
      ├─pve-vm--502--disk--1 251:8    0     5G  0 lvm
      ├─pve-vm--503--disk--1 251:9    0    20G  0 lvm
      ├─pve-vm--503--disk--2 251:10   0    50G  0 lvm
      └─pve-vm--506--disk--1 251:12   0    22G  0 lvm

But neither "mount" nor "fdisk -l" will show me the BIG LVM (pve-data 808.4G lvm) ...
So what to do (or what to mount) to get access to this BIG free space? I think it has something to do with the new/pre-installed "LVM thin support" -- but how to add free space there?

(I simply wanted to copy the backup via scp to that location...)
Thanks for a hint.

 

[dcsapak]

This big free space is used for a LVM Thin pool, which has not a filesystem and can not be mounted. Instead, when you create a VM there, it allocates a new logical volume in this thin pool.
for details see https://pve.proxmox.com/wiki/LVM2

depending on how big the backup file is, you can simply copy it on the root filesystem,
or you can temporarily use a usb drive/network share
or you can create a logical volume manually which you then can mount (see my previous link for a guide to this)

 

[tsumaru720]

Hi dcsapak,

What're the benefits for doing storage this way now? I installed a new node today and noticed local-lvm storage and lack of /dev/pve/data being mounted at /var/lib/vz

In my case as it was a fresh server, and to bring it in line with the rest of my cluster I have mounted it traditionally via fstab and ext4 but I am curious as to why you decide to use LVM subvols as the default option now

Thanks

 

[dcsapak]

What're the benefits for doing storage this way now?

for example:
snapshots (also for containers without zfs or ceph, etc.)
no additional filesystem layer between the disk and the containers/vms

 

[mir]

Hi dcsapak,

What're the benefits for doing storage this way now? I installed a new node today and noticed local-lvm storage and lack of /dev/pve/data being mounted at /var/lib/vz

In my case as it was a fresh server, and to bring it in line with the rest of my cluster I have mounted it traditionally via fstab and ext4 but I am curious as to why you decide to use LVM subvols as the default option now

Thanks

You could manualle create a volume in the pool and mount it on /var/lib/vz

 

[tsumaru720]

If I have an older install (that was Proxmox 3) but has been upgraded to Proxmox 4, what would the process be to convert the existing pve-data volume to be in line with your now recommended practices?

(Obviously will back up existing VMs first)..

I assume something along the lines of:

• Back up VMs
• Unmount /var/lib/vz
• Remove from /etc/fstab
• Remove pve-data volume
• Create new volume in line with how proxmox now provisions it?
• Add new storage type LVM-Thin using the new pve-data volume?
• Re-import VMs using the new storage volume

Am I missing anything?

 

[tsumaru720]

*bump* ?