Archive for the ‘centos’ Category

Viewing package ChangeLog with rpm

Monday, April 4th, 2016

Here is how to view the ChangeLog of installed package using rpm under CentOS:

  1. rpm -q —-changelog libuuid-2.23.2-26.el7_2.2.x86_64 | more
  2.  
  3. * Wed Mar 16 2016 Karel Zak <kzak@redhat.com> 2.23.2-26.el7_2.2
  4. – fix #1317953 – lslogins crash when executed with buggy username

Same applies to the kernel. By adding -p switch you can actually check the rpm file itself without installing it:

  1. rpm -qp —-changelog kernel-plus-3.10.0-327.13.1.el7.centos.plus.x86_64.rpm | more
  2.  
  3. * Thu Mar 31 2016 Akemi Yagi <toracat@centos.org> [3.10.0-327.13.1.el7.centos.plus]
  4. – Apply debranding changes
  5. – Roll in i686 mods
  6. – Modify config file for x86_64 with extra features turned on including

Unattended installation of CentOS 7 with Kickstart

Sunday, March 13th, 2016

While setting up my first Hadoop cluster I faced with the dilemma of how to perform installations of CentOS 7 on multiple servers at once. If you have 20 data nodes to deploy, anything you chose to automate an installation will greatly reduce the deployment time, but most importantly, it will eliminate the possibility of human error (typo for example).

Initially, I started looking at the disk cloning direction. Since all my data nodes are identical, I was thinking to prepare one data node server, then dd the system drive, place it on a NFS share, boot the server and re-image the system drive using dd image from the share. Clonezilla and DRBL seem to be the perfect pair for a such scenario. And although you will spend some time configuring, testing and tuning it, it was still worth to look into it.

Then I realized that even if I manage to establish the setup above, I’ll still have to deal with manual post-installation tweaks, like regeneration of SSH keys and probably adjusting of MAC addresses. On top of that, to transfer raw dd image (in my case it was ~30GB) might take longer than initial installation itself. Therefore I ended up using Kickstart method. I’m pretty sure there are more efficient solutions and if you happen to know one I’d love to hear your comments.

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