Linux: Command Belongs To Which RPM

If you want to install a Command and not sure which package it belongs to. Here are the steps:

[root@vm1 /]# nslookup vm1
-bash: nslookup: command not found

I am trying to use "nslookup" but it does not exist on the server.

But I have CD mounted with repository configured.

Now find out which RPM has the command.

root@vm1 /]# yum whatprMatched from:

Filename    : /usr/share/zsh/4.3.10/functions/nslookup

32:bind-utils-9.8.2-0.7.rc1.el6.x86_64 : Utilities for querying DNS name servers

Repo        : cluster

Matched from:

Filename    : /usr/bin/nslookup

32:bind-utils-9.8.2-0.7.rc1.el6.x86_64 : Utilities for querying DNS name servers

Repo        : server

Matched from:

Filename    : /usr/bin/nslookup

zsh-4.3.10-5.el6.x86_64 : A powerful interactive shell

Repo        : server

Matched from:

Filename    : /usr/share/zsh/4.3.10/functions/nslookup

So, You can install any of the above RPM to get the Command. :)

Linux: Show the number of CPU cores and sockets on your system

dmidecode -t 4 |grep Thread # number or cpu listed as well by cat /proc/cpuinfo

dmidecode -t 4 |grep CPU # number of physical CPU

Appending groups to a user

For example, if testuser is a member of  group1 and group2, and you need to add the user to group3, the command would be:

usermod -G group1,group2,group3 testuser

If you mistakenly ran:

usermod -G group3 testuser

Then testuser would be removed from group1 and group2 and only be a member of group3.

Add a node to a 2 Node Cluster : RHEL

[root@node1 ~]# clustat
Cluster Status for oracle @ Thu Feb 20 00:56:32 2014
Member Status: Quorate

 Member Name                                                     ID   Status
 ------ ----                                                     ---- ------
 node1                                                               1 Online, Local
 node2                                                               2 Online

[root@node1 ~]#


[root@node2 ~]# clustat
Cluster Status for oracle @ Mon Feb 17 07:20:55 2014
Member Status: Quorate

 Member Name                                                     ID   Status
 ------ ----                                                     ---- ------
 node1                                                               1 Online
 node2                                                               2 Online, Local

[root@node2 ~]#

I am going to add a new node called "node3". This can be done from LUCI or CLI.

From the primary node, update the cluster.conf

[root@node1 ~]# vi /etc/cluster/cluster.conf
[root@node1 ~]# cat /etc/cluster/cluster.conf
<?xml version="1.0"?>
<cluster config_version="15" name="oracle">
        <clusternodes>
                <clusternode name="node1" nodeid="1"/>
                <clusternode name="node2" nodeid="2"/>
                <clusternode name="node3" nodeid="3"/>
        </clusternodes>

[root@node1 ~]# cman_tool version -r
[root@node1 ~]# clustat
Cluster Status for oracle @ Thu Feb 20 01:05:07 2014
Member Status: Quorate

 Member Name                                                     ID   Status
 ------ ----                                                     ---- ------
 node1                                                               1 Online, Local
 node2                                                               2 Online
 node3                                                               3 Offline

[root@node1 ~]#

Now start the CMAN service on node3:

[root@node3 ~]# service cman start

Starting cluster:

   Checking if cluster has been disabled at boot...        [  OK  ]

   Checking Network Manager...                             [  OK  ]

   Global setup...                                         [  OK  ]

   Loading kernel modules...                               [  OK  ]

   Mounting configfs...                                    [  OK  ]

   Starting cman...                                        [  OK  ]

   Waiting for quorum...                                   [  OK  ]

   Starting fenced...                                      [  OK  ]

   Starting dlm_controld...                                [  OK  ]

   Starting gfs_controld...                                [  OK  ]

   Unfencing self...                                       [  OK  ]

   Joining fence domain...                                 [  OK  ]

[root@node3 ~]# 

[root@node3 ~]# clustat

Cluster Status for oracle @ Wed Feb 19 08:52:40 2014

Member Status: Quorate

 Member Name                                           ID   Status

 ------ ----                                           ---- ------

 node1                                                     1 Online

 node2                                                     2 Online

 node3                                                     3 Online, Local

[root@node3 ~]#

Simple ...:)

Flushing The Multipath

# multipath -F : Command to Flush the multipath table, after the LUN's are unassigned from the server.

Note: After flushing the path, you may still face "tur checker error".

Linux Interview Questions

1) Linux Boot Process.
2) Linux Storage Lun Detection.
3) How to see WWID of a Lun.
4) Crash Dump Configuration.
5) Explain  free command output.
6) How to view HBA WWPN in linux.
7) Cluster status command
8) Resource Group fail over in Linux.
9) Bonding  Types
10) Patching.

Please join my site to get the answers with example.

Starting cman... cman_tool: Cannot open connection to cman, is it running ? Check cluster logs for details

/var/log/messages:

Jan 26 20:25:28 node2 corosync[2426]:   [CMAN  ] Unable to load new config in corosync: New configuration version ha     s to be newer than current running configuration
Jan 26 20:25:28 node2 corosync[2426]:   [CMAN  ] Can't get updated config version 32: New configuration version has      to be newer than current running configuration#012.
Jan 26 20:25:28 node2 corosync[2426]:   [CMAN  ] Activity suspended on this node
Jan 26 20:25:28 node2 corosync[2426]:   [CMAN  ] Error reloading the configuration, will retry every second
Jan 26 20:25:28 node2 corosync[2426]:   [CMAN  ] Checking for startup failure: time=1
Jan 26 20:25:28 node2 corosync[2426]:   [CMAN  ] Failed to get an up-to-date config file, wanted 32, only got 31. Wi     ll exit

Looks like the issue with the cluster version and that the reason the node is if offline state.

 Member Name                                                     ID   Status

 ------ ----                                                     ---- ------

 node1                                                               1 Online, Local

 node2                                                               2 Offline

[root@node1 ~]# ccs -h node1 --sync : Command to sync the cluster.conf file across the nodes.

[root@node2 ~]# service cman start

Starting cluster:

   Checking if cluster has been disabled at boot...        [  OK  ]

   Checking Network Manager...                             [  OK  ]

   Global setup...                                         [  OK  ]

   Loading kernel modules...                               [  OK  ]

   Mounting configfs...                                    [  OK  ]

   Starting cman...                                        [  OK  ]

   Waiting for quorum...                                   [  OK  ]

   Starting fenced...                                      [  OK  ]

   Starting dlm_controld...                                [  OK  ]

   Starting gfs_controld...                                [  OK  ]

   Unfencing self...                                       [  OK  ]

   Joining fence domain...                                 [  OK  ]

[root@node2 ~]#

 Member Name                                                     ID   Status

 ------ ----                                                     ---- ------

 node1                                                               1 Online, Local, rgmanager

 node2                                                               2 Online