How to shrink a filesystem in Linux

November 28, 2011
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This does not happen often, but you may run into a situation where you need to reduce the size of the Linux filesystem. Well, in my case I wanted to clone my Red Hat Enterprise Linux server which was running in Vmware ESXi. The root filesystem was originally built too large and I wanted...
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How to extend the filesystem on a Vmware ESX guest Red Hat Linux server

May 26, 2011
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Being the administrator of a large Linux shop, I have had to extend the filesystems on the Red Hat Linux server a few times. Each time I had the opportunity to extend the filesystem, I found that I struggled to remember the commands and...
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Unable to login to remote server via ssh

May 18, 2011
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A funny thing happened to one of my Red Hat 5 Enterprise servers after applying the errata. I rebooted the servers as usual after applying the updates, and they came up just fine. But unfortunately I was not able to logon remotely via ssh...
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How to create a new superuser in Linux

May 17, 2011
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The administrative account ‘root’ is the most powerful user in Linux and Unix. This account is created by default during installation of the operating system. Most security consultants will recommend that the root account be deleted or renamed. This is to make it harder...
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Troubleshoot problem with yum update and rebuild the rpm database

March 23, 2011
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I have created a step by step approach to troubleshoot a problem with performing yum update and how to rebuild the rpm database. I received and error while trying to update the Redhat Enterprise 5 server kernel using yum update. Looking at the output...
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Booting Red Hat Linux into rescue mode.

January 28, 2011
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Booting Red Hat Linux into rescue mode.

Red Hat Linux can be booted into rescue mode from the installation CD, or any other boot method instead of the system’s hard drive. This also applies to other versions of Linux such as Fedora and Centos. The rescue mode is provided for troubleshooting...
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Identifying the kernel version and changing the default boot kernel in RedHat and Centos Linux.

January 27, 2011
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Use the command uname to print system information in Linux. # uname -r 2.6.18-194.32.1.el5 The –r option will print the kernel release. # uname -s Linux -s prints the kernel name. # uname -n mycomputer.wiivil.com Print the node name or hostname. # uname -p...
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Nslookup resolves address but ping is unable to resolve hostname on Unix server

November 17, 2010
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I came across this issue on my newly built Solaris 10 server. I was able to ping a remote machine by Ip address, but not by its hostname. This indicated that I had the correct route and gateway. Using nslookup and dig I verified...
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How to map to a remote NFS directory from a VMware ESX 4 server.

November 16, 2010
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I ran into this error while trying to mount a NFS directory on a remote server from my Vmware ESX4 server. My Vmware esx server is called esx4-server and the remote NFS server is called remote-server. I executed the mount commant and got the...
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Sun Sparc commands to power on and boot up the server.

November 15, 2010
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Booting up the Sun Sparc M3000 server. After logging into the XSCF console, power on the server. XSCF> poweron -d 0 DomainIDs to power on:00 Continue? :y Switch to the server console. XSCF> console -d 0 Connect to DomainID 0? :y Devalias will...
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Creating RDM to LUN (SAN) mapping on VMware ESX 4, Vcenter.

August 6, 2010
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In the past I have written articles about how to create a RDM to LUN disk mapping for VMware ESX 3. http://www.gamescheat.ca/2009/10/scripts-to-automate-the-process-of-identifying-and-compiling-an-rdm-to-lun-mapping-list-for-vmware-esx-30/ and http://www.gamescheat.ca/2009/10/how-to-identify-and-compile-an-rdm-to-lun-mapping-list-for-vmware-esx-30/ The procedure to identify the path for the RDM (raw disk mapping) to LUN (disk on SAN) on Vmware ESX...
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Booting up Solaris 10 from a SAN replicated LUN on a different Sun SPARC server

July 9, 2010
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The quickest way to recover from a total disaster is to have some sort of replication implemented. There are two different methods of real-time replication, hardware and software. My experiences with software replication such as Symantec Veritas Volume replicator for AIX was not pleasing....
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How to get the network card speed in Solaris 9

May 12, 2010
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To determine the network card speed in Solaris 9 use the ndd utility. First list the NIC installed and active on the Solaris 9 server. # ifconfig -a lo0: flags=1000849 mtu 8232 index 1 inet 127.0.0.1 netmask ff000000 hme0: flags=1000843 mtu 1500 index 2...
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How to relocate the /export and /export/home filesystems on Solaris 10.

April 8, 2010
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By default Solaris installs the /export and /export/home filesystems in the root zfs pool, if you picked ZFS and not UFS as the filesystem. I wanted to relocate /export and /export/home to a larger ZFS pool other than the root pool as I wanted...
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How to rebuild a Solaris 10 server using the ZFS Root Pool Snapshots

March 12, 2010
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Solaris 10 has provides the ability to recover from a disk drive failure using ZFS root pool snapshots. The snapshot can also be used to quickly rebuild a new server in the event of a disaster. Snapshot is different from flash archive which can...
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