The Problem On CentOS/RHEL system, the messages file is empty, and so are the rotated files (exact rotated names depends on the /etc/logrotate.conf configuration file), e.g. : # cd /var/log ls -larth messages* -rwxrwxrwx 1 root root 0 Aug 8 22:32 messages.4 -rwxrwxrwx 1 root root 0 Aug 15 22:32 messages.3 -rwxrwxrwx 1 root root 0 Aug 22 22:32 messages.2 -rwxrwxrwx 1 root root 0 Aug 29 22:32 messages.1 -rwxrwxrwx 1 root root 0 Sep 5 22:32 messages The Solution The /etc/syslog.conf … [Read more...] about The /var/log/messages is empty, and so are the rotated log files such as messages.0, messages.1
Linux
System Log File /var/log/messages Is Getting Deleted or Trimmed Automatically (CentOS/RHEL)
The Problem The system log /var/log/messages are getting trimmed or deleted automatically, and the old log will not be rotated to messages.1, messages.2, or so. The Solution The system log will be rotated by the logrotate, a cron job scheduled daily. This problem is due to an incorrect logrotate configuration. Checking the logrotate configuration file /etc/logrotate.conf below: # rotate log files weekly #weekly # keep 40 weeks worth of backlogs #rotate 40 the rotation … [Read more...] about System Log File /var/log/messages Is Getting Deleted or Trimmed Automatically (CentOS/RHEL)
How to Transfer a File In Passive Mode by FTP
By default vsftpd will use passive mode for transferring: # man vsftpd pasv_enable Set to NO if you want to disallow the PASV method of obtaining a data connection. Default: YES If the user wants to customize the ports information used, or to enable active mode, then do the following: 1. modify /etc/vsftpd/vsftpd.conf and add below lines: pasv_enable=NO pasv_min_port=49152 pasv_max_port=65534 2. Restart the vsfptd service for the above configuration to take effect. # … [Read more...] about How to Transfer a File In Passive Mode by FTP
How to Limit some User Memory Resources on CentOS/RHEL using cgroup
Question: How to limit user "testme" memory resources, for example, the user "testme" will be only able to get 100mb of memory from the System. ulimit won't be able to achieve this goal as ulimit limit user memory consumption per process - in this case, the customer would like to set user "testme" memory quota to 100mb. 1. To achieve simple solution of limiting users memory resources is to do: # vi /etc/cgconfig.conf Add there: group memlimit { memory { memory.limit_in_bytes = … [Read more...] about How to Limit some User Memory Resources on CentOS/RHEL using cgroup
How to Increase the File Download Size Limit in Apache
The Problem You may encounter a request to increase the file download size limit in Apache server. Attempting to call a URL to upload a file, the following error occurs in Browser: ERROR Request entity too large. Request exceeds the capacity limit Apache error_log has the following error: Request content-length of 294135 is larger than the configured limit of 262144 The Solution The file download size limit is controlled by the Apache directive "LimitRequestBody". By default, it … [Read more...] about How to Increase the File Download Size Limit in Apache
How To Configure Separate Override.conf For Multiple MySQL Instances Using Systemd
If the system services are managed by systemd, the systemd daemon should be aware of the PID file location of process to start/stop/restart it. On a system with systemd support, "override.conf" is used to specify both "PIDFile" and "ExecStart" with PID file location. Any setting of the process ID file in MySQL option file (my.cnf) is ignored. This post covers the case when we need to create a separate "override.conf" files for multiple MySQL instances management on the same server. In the … [Read more...] about How To Configure Separate Override.conf For Multiple MySQL Instances Using Systemd
How to Disable “Predictable Network Interface Device Names” in CentOS/RHEL 7
On a CentOS/RHEL 7, the network interface will be named like enoxxx. This post provides steps on how to disable such "Predictable Network Interface Device Names". We can use the following ways to disable the predictable network interfaces: 1. Create your own manual naming scheme by defining your own udev rules file in /etc/udev/rules.d folder and set the NAME property for the devices. Make sure to order it before the default policy file which is … [Read more...] about How to Disable “Predictable Network Interface Device Names” in CentOS/RHEL 7
How to Disable/Enable Numa for Virtual Machine (XEN based)
How to check if NUMA is enabled To determine if the server is a NUMA-based system with NUMA enabled, run the following command as root on the database server: # numactl -H | grep available available: 8 nodes (0-7) - or - # numactl -H | grep available available: 2 nodes (0-1) If the number of available nodes is "2 nodes (0-1)" or "8 nodes (0-7)" then NUMA is enabled. If the number of available nodes is "1 nodes (0)" then NUMA is not enabled. How to disable Numa on Virtual … [Read more...] about How to Disable/Enable Numa for Virtual Machine (XEN based)
LVM and multipathing – sample LVM filter strings
The post is intended for Linux System Administrators seeking to initially configure or further optimise existing LVM configured systems. It discusses: the need for specific LVM filter string configuration for the particular storage type in use. provide sample LVM filter strings for a variety of common storage devices LVM Configuration - filter parameter The primary LVM configuration file is /etc/lvm/lvm.conf. The file consists of a number of sections each containing various … [Read more...] about LVM and multipathing – sample LVM filter strings
lvdisplay error: “Failed to create directory /var/lock/lvm. File-based locking initilisation failed.”
The Problem lvdisplay command prints the below error on a CentOS/RHEL 6 system: # lvdisplay Failed to create directory /var/lock/lvm File-based locking initilisation failed. The Solution The above error is due to the /var file system is mounted as read only. To resolve the issue, follow the steps outlined below: 1. Edit and modify /etc/lvm/lvm.conf as below: locking_dir = "/var/lock/lvm" to locking_dir = "/tmp/lock/lvm" 2. Run the lvm commands by defining temporary locking … [Read more...] about lvdisplay error: “Failed to create directory /var/lock/lvm. File-based locking initilisation failed.”