LRZ_mount_DSS

Mounting the DSS at a VM

This section covers a minimum example mounting (NFS) a DSS Container on a VM including a Compute Cloud VM. The only limitation is, that the VM (IP) has to be located in the LRZ data center.

Prepare the DSS Container

1. Make sure you have the ‘Is Manager’ right for the DSS container on https://dssweb.dss.lrz.de (in case, someone of the ECP group has to give it to you).
2. log in at: dssweb.dss.lrz.de (only accessible in the ‘mwn’, in case use a VPN connection)
3. select the DSS container. You should see: ‘DSS Container Details’
4. Make sure you have the ‘Is Manager’ right for the DSS container in dssweb.dss.lrz.de. ( in case another Manager have to give it to you).
5. Add the ‘Funktionskennung’ of the VM (the one you need to set up the VM in the Compute Cloud) to the container user
   1. At Container User click Add new user and add the Funktionskennung
   2. Accept the invitation coming by mail (the person which is liked to the Funktionskennung)
6. At NFS Exports click Add new export and add the a IP of the VM (Floating IP for the Compute Cloud VM; the IP you will find at: https://cc.lrz.de/project/ -> Project -> Compute -> Instances)
7. keep the tab open, you’ll need the Mount Path (which is <IP>:<Path>) later.

Create the users with the right UID on the VM

1. log in to the VM via ssh ...
2. In another tab, log in to: ssh ab12cde@dsscli.dss.lrz.de (called dsscli in the following); replace ab12cde with your LRZ ID (not the Funktionskennung). (Only accessible in the mwn, in case use a VPN connection).
   1. type login and log in with your LRZ ID and Password
   2. do the steps under 11.6. NFS helper functions from the official docs which are:
      1. On dsscli: dss passwd list --containername pr74qo-dss-0000 pr74qo ; replace: pr74qo-dss-0000 with your container name and pr74qo with your project name (you will find the information in the tab from above, dssweb.dss.lrz.de)
      2. On the VM: Add the returned lines to: /etc/passwd, (e.g., with sudo vim /etc/passwd)
      3. Do the same with dss group list --containername pr74qo-dss-0000 pr74qo on dsscli to /etc/groups on the VM
      4. Now you have successfully added new user to the VM (passwords aren’t set)
      5. alternatively: if it is just one user, you can use: sudo useradd -m -u <uid> <user>
   3. You can close the connection to dsscli, (contr. + C)
   4. Comment: you can also just extract the UID form a listed user ❌1234567:2222::/home/:-> 1234567. Change the UID on the VM of an existing user with useradd -u 1234567 <username_2> (This could cause some side effects like permission to the home directory). As for NFS, only the UID is important.
3. Set a password for one of the added user with: sudo passwd <username> (can be anything)
4. Check: you can check the UID with id <username> on the VM

Mount the Container

1. This is the summary of: 2.2.3. Mounting a DSS Container on a VM of the official docs
2. Create a new directory where the DSS is mounted to, here /dss and mount it. Replace <IP>:<Path> with the Mount Path from Prepare the DSS Container

  sudo mkdir -p /dss
  sudo apt-get install nfs-common
  sudo mount -t nfs -o rsize=1048576,wsize=1048576,hard,tcp,bg,timeo=600,vers=3 <IP>:<Path> /dss

1. Check: You can check with df -h /dss or mount if the <Path> is listed
2. Add it to /etc/fstab for automated mount
   1. modify the file with: sudo vim /etc/fstab
   2. add the line and replace <IP>:<Path> with the Mount Path from Prepare the DSS Container

      <IP>:<Path> /dss  nfs    rsize=1048576,wsize=1048576,hard,tcp,bg,timeo=600,vers=3    0       0

   3. save and close the file
   4. to check if it works

      sudo umount /dss 
      sudo mount /dss   # this is now enough, it reads the settings from /etc/fstab

   5. now the DSS is mounted automatically after a reboot

Use the Container

1. Comment: Only the users with the correct UID’s can access the /dss (The root-user (i.e. sudo <cmd> ) does not work here as it is set to nobody which is the wrong UID)
2. Option 1: change the user for the one CMD only
   1. sudo -u <username> <cmd> , e.g. sudo -u <username> ls /dss
3. Option 2: change the user
   1. su - <username> + enter the password you set before in the section
   2. execute a <cmd> , e.g. ls /dss