Overview

After installing Kerio Control from a downloaded .iso image, users may encounter a system freeze upon reboot. The initial installation appears successful, but the appliance fails to boot fully. 

Upon pressing a key at the freeze point, numerous "read-only file system" errors appear, alongside tune2fs and mount-related issues referencing /dev/sda4.

Symptoms:

• System freezes after first reboot (post-install).

• Error: tune2fs: Bad magic number in super-block while trying to open /dev/sda4.

• Mount errors: /dev/sda4 on /var failed: Invalid argument.

• Multiple cp: cannot create... Read-only file system messages.

Solution

This is known to happen when Kerio Control .iso image is deployed on a drive that was initially formatted with an unsupported partition filesystem (for example ZFS).

Step 1: Boot with GParted Live or Any Linux Live OS

1. Download GParted Live ISO or use a Linux distribution with GParted preinstalled (e.g., Ubuntu).

2. Boot the appliance from the USB stick or CD.

Step 2: Launch GParted

1. Once booted, open GParted.

2. Select the correct disk (usually /dev/sda).

3. Delete all partitions:

   • Right-click each partition and choose Delete.

   • Do this for all visible partitions (ZFS or otherwise).

4. Apply all changes by clicking the green ✔️ button.

Step 3: (Optional) Create a New ext4 Partition

1. Still in GParted, click New to create a partition.

2. Set:

   • File system: ext4

   • Partition label: (optional)

3. Click Apply.

Step 4: Reboot and Install Kerio Control

1. Remove the GParted USB.

2. Re-Initiate the process for Installing Software Appliance on bare-metal server

Summary

If Kerio Control freezes on boot after installation and displays file system errors (likeBad magic number in super-block while trying to open /dev/sda4), it's likely due to disk format issues or corrupted partitions. Use GParted to delete all existing partitions (especially ZFS) before installation. 

Frequently Asked Questions (FAQ)

Q1: Why does Kerio Control say "Bad magic number in super-block"?
A1: This error usually means the partition is not formatted with a valid Linux file system, or it's corrupted.

Q2: Can I use other tools besides GParted?
A2: Yes — tools like wipefs, fdisk, or parted in a Linux Live USB session will also work.

Q3: What type of file system should Kerio Control use?
A3: Kerio Control installs its own optimized Linux partition scheme during setup. Ensure no external formatting is done beforehand.