Besides the RAM there is a so called Swap, which is a virtual memory, where RAM content (pages) could be swapped-in in case there is not enough RAM available anymore. This swap is located on the disc and since disc reads and writes are slower than reading from RAM, accessing memory pages there will result in a delay. In addition to filesystem creation, Linux administrators also has to pay close attention to swap usage and needs. The post describes 3 ways to add swap space to Linux systems: 1. … [Read more...] about How to add swap space in linux
Archives for October 2015
Solaris : How to create processor set (pset) and associate it with a pool
Resource pools provide a mechanism for partitioning a system into persistent processor sets with optional scheduling class assignments. Pools even work with Dynamic Reconfiguration (DR). The post describes how to create a processor set and associate it with a pool. Before a processor pool can be created, the svc:/system/pools:default service must be enabled. It can be verified with the following command: # svcs -l svc:/system/pools:default fmri svc:/system/pools:default name … [Read more...] about Solaris : How to create processor set (pset) and associate it with a pool
Solaris : How to set limit on the maximum number of open files per process
The maximum limit of open files per process can be limited by setting a hard limit and/or a soft limit. The hard limit can be set by the system administrator and be decreased by any user, whereas the soft limit can be set by any user, up to the hard limit. This document describes the various methods available in Solaris 10 and Solaris 11 for setting the limit for the maximum number of open files per process. Types of limits 1. hard limit : The hard limit (/etc/system parameter rlim_fd_max or … [Read more...] about Solaris : How to set limit on the maximum number of open files per process
Solaris : How to find number of open files by a process
Sometimes, the error message "too many open files" is displayed in /var/adm/messages. In these cases, it is often useful to know how many files are currently open by a process. The number of files currently opened by a certain process can be examined by: 1. The pfiles command 2. Using the /proc file system Using pfiles command The pfiles command displays the current limit of the number of open files for the process and more information about all currently open files of that process. See … [Read more...] about Solaris : How to find number of open files by a process
CentOS / RHEL : How to collect sosreport
The "sosreport" is a tool to collect troubleshooting data on RHEL/CentOS systems. It generates a compressed tarball of debugging information that gives an overview of the most important logs and configuration of a Linux system, to be sent to Redhat Support. Among other things, the sosreport includes information about the installed rpm versions, syslog, network configuration, mounted filesystems, disk partition details, loaded kernel modules and status of all services. To run sosreport, the … [Read more...] about CentOS / RHEL : How to collect sosreport
CentOS / RHEL 7 : How to Reset root password
Resetting root password in CentOS/RHEL 7 is slightly different than the older versions. The post describes the procedure to reset the lost root password. Reboot and edit grub2 Reboot the system and press any key to stop the auto-boot from the default kernel. Press "e" after selecting the kernel line. Append rd.break to kernel When you are in edit mode, go to the line starting with linux16 and append rd.break to the end of this line. Reboot the system Press CTLR+x after … [Read more...] about CentOS / RHEL 7 : How to Reset root password
How to troubleshoot Solaris 10 SMF (Service Management Facility) related issues
Service management facility was first introduced in Solaris 10 for managing system and application services. This replaces the legacy init scripts and other startup scripts. The post discusses few basic troubleshooting techniques to resolve the SMF (Service Management Facility) related issues. Logfiles, Manifests and Methods 1. SMF logfiles can be found in the following locations: /var/svc/log /etc/svc/volatile 2. The SMF manifests and methods may be found … [Read more...] about How to troubleshoot Solaris 10 SMF (Service Management Facility) related issues
Troubleshooting solaris 10 boot issues related to SMF and milestones
The post describes few troubleshooting tips for resolving the boot issues related to SMF(Service Management Facility). We can boot to early milestones and can go from one level to the next. this way we can identify the milestone causing the issues and eventually the service causing it. General troubleshooting Before going into more detailed troubleshooting, we can enable a more verbose debugging while booting the server. Look at results of below booting commands to check for any error … [Read more...] about Troubleshooting solaris 10 boot issues related to SMF and milestones
How to install a ZFS boot block in solaris
The post discusses about how to install ZFS boot block on a system running a ZFS root filesystem. This is normally required when a system fails to boot from a disk containing a root filesystem. A typical error may include: The file just loaded does not appear to be executable Bootblk: can't find the boot program. Solution Boot from DVD/network/failsafe image In order to install a new ZFS boot block, you need to first boot from DVD, network or the failsafe image on the system. ok> boot … [Read more...] about How to install a ZFS boot block in solaris
lsof : Most commonly used examples
The lsof command lists open files, sockets, and pipes. You can use lsof command to see what files are held open (such as libraries or log files) and what ports daemons listen to. You can search for open files using lsof command. lsof should be run as the superuser (root) to see all open files. When used without any arguments/options lsof lists all open files for the current active processes. # lsof COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME init … [Read more...] about lsof : Most commonly used examples