Failure Analysis

In the long-term operation of the Unisys UOS system, some programs report errors, continuously write system logs, and the output error messages are too frequent,

which leads to a crazy growth of the log file, and ultimately leads to the root directory space is occupied, the system has no remaining space, and users can not log in.

Troubleshooting

Enter into single-user mode and empty the log file.

1) At the boot grub menu, press the direction "↓" key to position the cursor to the Uniontech OS Backup & Restore menu;

2) Press E to enter grub menu edit mode;

3) splash quite change to systemd.unit=multi-user.target, then press CTRL+X to enter into single-user mode;

4) Find the big log file:

a.Type sudo -s to switch to the root user;

b. Enter fdisk -l to view the disk partition, and find that the sda5 partition is 50G;

c. Find the root partition to mount;

Use the command to mount the sda5 partition on the /mnt directory and confirm that there are var, lib, usr directories under /mnt, then you can confirm

that sda5 is the root partition, if not then you need to try other partitions.

mount /dev/sda5 /mnt

ls -l /mnt

Type df -h to see the file system usage.

d. Find the large directory in the /mnt directory;

Use the following command:

du --max-depth=1 -BM /mnt/ | sort -nk1

The output shows that the /mnt/var directory is very large. Find files larger than 5 gigabytes in the /mnt/var directory.

cd /mnt/var

du --max-depth=1 -BM /mnt/var | sort -nk1

The output shows that the /mnt/var/log directory is very large, look for files larger than 5G under /mnt/var/log.

du -sh /mnt/var/log/*.

Note: The file kern.log.1 exceeds 5G and has reached 41G.

Empty the log files larger than 5G found by using the command (filenames are based on the larger files output by find).

truncate -s 0 /mnt/var/log/

Use the df -h command to see the space being freed as shown below.

e. Input reboot command to reboot the machine can be normally logged into the domestic Unisys UOS system.