Troubleshooting a VPS in expert mode

Problems logging in

Server not responding

I get the message "E: Couldn't find package" when installing an application

See using apt-get for deb based distribution (like Debian or Ubuntu). For rpm based distribution, you will have to use the dedicated tool from the distribution : yum for Fedora, CentOS, urpmi for Mandriva, …

Cannot upload files to my remote server

I get the message WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! when I try to connect to my server

  1. if you didn't change anything on your server, this could indicate that your server was compromised. Use the emergency console to connect to your server. Another solution could be to stop the server and attach the system disk to another server to check if someone has broke into your server.
  2. if you delete a virtual server and created a new one which get the same IP address to the previous one, you can safely remove the public key store locally in your keychain :
ssh-keygen -R your_ip_address

Other

FIXME

  • I can not find the “XXXX” module in the operating system on my server.

here : Updating kernel modules.

  • I have an error when updating .deb package made by Gandi

here : How to fix error when updating packages.

  • How to configure gandi-config service in gandi-hosting-vm package ?

The gandi-hosting-vm package is installed by default on all OS image prepared by our technical team. It install files in their correct path and you can modify its behavior at boot time with this config file : /etc/sysconfig/gandi. More information in : http://lacuisinedegandi.net/post/2010/10/28/Modification-des-OS-standards-par-Gandi

  • The resize2fs command did nothing on my VPS when I increased the size of a disk, df -h returns me the same size !

Update the gandi-hosting-vm package using Gandi APT sources
Stop / start your VPS in two times on the control panel
Do the procedure described on our wiki again

  • I try to detach a disk from my server and the operation is still in error

When detaching a disk and if no incident on our hosting plaform has been published, the main cause is a running application still using files on the currently detaching disk. When the kernel cannot release the disk to the Xen subsystem, it print a message in the 'dmesg' output.

By using either 'lsof' of 'fuser' command, you can try to identify which process in memory is using the disk and blocking the detach operation.

  • On CentOS, iSCSI errors appear every second in the logs, after a while the disk is full

CentOS is installing by default iscsi and iscsid, you can remove those packages, or just stop it, that will have no impact on the VPS, we use it for the backend but not on the VPS, this will avoid the logs errors.

  • On CentOS, Gsync returns errors, it missed some python dependances : “ImportError: No module named ctypes”

It is necessary to follow this process :

- install & activate the EPEL repository - install the python-ctypes package

And Gsync works ! (Thank to Christophe Gimenez for the report).

  • I upgraded the kernel of my VPS, the VPS crashes, I have a data disk formatted using XFS

The new kernels are not supporting XFS anymore, you have to create a new disk on our platform which will be formatted as Ext4, then transfer your files.

  • Data disks no longer auto-mount at boot

A recent update to systemd broke udev mounting on older CentOS 7 images. To correct this, create the following directory and file as root :

# mkdir /etc/systemd/system/systemd-udevd.service.d/
# touch /etc/systemd/system/systemd-udevd.service.d/local.conf

And add the following lines to the file :

[Service]
MountFlags=shared
Last modified: 04/25/2017 at 00:48 by Richard M. (Gandi)