Archives for September 2018

There are many tools/utilities that can be used to analyze the current system performance. But how do we gauge the historic system performance? For that you can use the System Activity Report (SAR) tool. Using the sar tool, you will be able to look back over a period of time and see how the server […]

The post outlines the steps to configure passwordless ssh between 2 CentOS/RHEL hosts. The steps although remains almost the same with slight changes across all the Linux distributions. 1. Log in as the user that you want to set up the ssh keys, in this case, we are using user “geek”. 2. Create a private […]

Here is a short post to check port [TCP/UDP] connectivity from a Linux server. A TCP/IP network connection may be either blocked, dropped, open, or filtered. These actions are generally controlled by the IPtables firewall the system uses and is independent of any process or program that may be listening on a network port. Telnet […]

This post will cover the most frequently reported how-to questions of Enterprise Linux Common Package Manager (RPM). Although not often used, rpm is a must know when you are facing a Linux interview. What is RPM? RPM stands for Red Hat Package Manager which provides for installing, upgrading and removing packages on Linux distributions. It […]

The Problem Server failed to login through ssh with below errors. From ssh client: $ ssh -vvv root@10.131.12.10 OpenSSH_7.6p1, LibreSSL 2.6.2 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 48: Applying options for * debug2: ssh_connect_direct: needpriv 0 debug1: Connecting to 10.131.12.10 port 22. debug1: Connection established. debug1: key_load_public: No such file or directory debug1: […]

The Problem Executing the command “ntpq -pn” returns with the error: # ntpq -p Name or service not known In some cases, you may also encounter an error shown below: # ntpq -pn Servname not supported for ai_socktype The Solution The “Name or service not known” error will be seen if the system cannot resolve […]

Question When executing an ntpq -p command, what is the refid? $ ntpq -p remote refid st t when poll reach delay offset jitter ======================================================================================== *myntp.example.com 192.168.102.252 2 u 161 1024 377 0.841 -0.442 1.365 Answer A stratum-0 is an actual time source. It is connected to a server which is a stratum-1 server. Systems […]

The Problem Unable create or remove snapshot volume as error below: # lvcreate -s -L 3G -n snapopt /dev/vgOS/opt Logical volume “snapopt” already exists in volume group “vgOS” Whereas the logical volume is not present in any Volume Group. # lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert cplex vgOPT […]

Internet Small Computer System Interface (iSCSI) is an Internet Protocol (IP)–based storage standard that connects iSCSI initiators to iSCSI targets over IP networks. To put it simply, the SCSI packets are encapsulated in IP packets and sent over a standard IP network, where the initiators and targets reassemble the packets and interpret the commands carried […]

The Problem We can see the following error while unpacking a package using rpm command; — Preparing… ################################################## dbaastools ################################################## error: unpacking of archive failed on file /var/opt/xxxx/xxx/xxx/xxx/xxx.o.zip.xxxxx: cpio: read failed – Inappropriate ioctl for device How to correct this issue and to install the package successfully. The Solution RPM uses cpio as it’s archive […]