Tech Blog

XenServer Backup Script

I've seen a few XenServer backup scripts around but I decided none were exactly what I was looking for so I put one together myself.  My version has several configuration options including logging and compression.  It saves the images to an NFS share.

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An Active/Active Apache/MySQL Cluster

While I was working on the active/active iSCSI cluster, I began wondering if the same technology and concepts could be used to create a pair of active/active Apache/MySQL servers.  Turns out it can.  The primary issue to keep in mind is that in this setup, the potential exists for running 2 instances of both Apache and MySQL (actually MariaDB which is a drop-in replacement) on the same system.  So long as you have unique sockets (IP address + port) and the resources on each system to do so, that shouldn't be a problem.

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Resizing DRBD Storage on CentOS 7 Active/Active iSCSI Cluster

In this post, I am going to resize both DRBD resources created in my last post titled CentOS 7 Active/Active iSCSI Cluster with no down-time.  In fact, I will have 2 virtual mahines running, one per DRBD resource, while I make this change.  The primary consideration is that the backing device must have the ability to grow online (think LVM).  I'm using virtual machines so I will be able to enlarge the resources at the hypervisor level.  A lot of the information in this post comes from the DRBD site http://www.drbd.org/en/doc/users-guide-83/s-resizing.  I am just adding a few steps along the way and including some screen captures.

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CentOS 7 Active/Active iSCSI Cluster

In this post I am going to create an active/active high-availability iSCSI cluster using CentOS 7, pacemaker, corosync, pcs/pcsd, and DRBD.  I am not going to cover what each of these components do as I covered that in my previous article CentOS 7 active/passive Apache Cluster - Part 1 but I would recommend giving it a read.  I also want to mention that this setup is based on a technical publication found on the Linbit site, the makers of DRBD, at http://www.linbit.com/en/resources/technical-publications/.  There is additional information in that document as well as other technical publications that are well worth reading so I suggest everyone sign up and have a look at them by heading over to the Linbit site.  I am putting my own spin on the instructions plus I am using the pcs shell instead of crm since it is now used in RHEL/CentOS 7.

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