saravananlinux

QCOW2 Formatted Virtual Machine Storage QCOW2 is a storage format for virtual machine disk images. QCOW stands for QEMU copy on write. T he QCOW2 format decouples the physical storage layer from the virtual layer by adding  a mapping between logical and physical blocks. Each logical block is mapped to its physical offset, which enables storage over-comittment and virtual machine snapshots, where each QCOW volume only represents changes made to an underlying disk image. T he initial mapping points all logical blocks to the offsets in the backing file or volume. When a virtual machine writes data to a QCOW2 volume after a snapshot, the relevant block is read from the backing volume, modified with the new information and written into a new snapshot QCOW2 volume. T hen the map is updated to point to the new place. RAW T he RAW storage format has a performance advantage over QCOW2 in that no formatting is applied to virtual machine disk images stored in the RAW format. Virtual machi...

I have faced this issue in Joomla site and searched the forums but none of the forums including joomla did not give solution for me. They simply suggest to check joomla version, php version compatibility and php extensions. Finally I have fixed the issue. Issue:- ---------  [26-Sep-2014 18:11:29 Europe/Berlin] PHP Fatal error: Class 'JFactory' not found in /home/test/public_html/index.php on line 31 Cause & Solution:- ----------------------- In my case, it seems file which gives the class JFactory was missed. /home/test/public_html/libraries/joomla/factory.php --->Core file for Joomla. Simply restore that file under proper path to fix the issue.

PPT:- http://www.slideshare.net/slideshow/embed_code/37907628

1.Lsyncd - Live Syncing (Mirror) Daemon[Directory level] 2.DRBD.[block device level] 3. GlusterFS and BindFS use a FUSE-Filesystem to interject kernel/userspace filesystem events.  Reference: ----------------- https://code.google.com/p/lsyncd/ http://configure.systems/glusterfs-and-why-you-should-consider-it/ GlusterFS would actually mitigate and simply so much more of that. There would be no need for a Load Balancer, no need for a special script to promote, demote the content servers, nothing, not even to replicate the data between the servers! Basically, you can create two or more servers, install GlusterFS on each of the servers, have node all of the nodes probe the master node, then you would create the volume. Easy. Once that’s done, one your actual web nodes, where you have Apache, PHP, and again Varnish installed, you would install GlusterFS, add the correct line to the /etc/fstab, and you’re set. Within that line, you can even add a failov...

Reference: https://xrsa.net/2014/08/25/running-vmware-esxi-under-ovirt/

Refer: http://www.thegeekstuff.com/2011/02/linux-boot-process/

Storage pools and volumes are not required for the proper operation of guest virtual machines. Pools and volumes provide a way for libvirt to ensure that a particular piece of storage will be available for a guest virtual machine, but some administrators will prefer to manage their own storage and guest virtual machines will operate properly without any pools or volumes defined. NFS storage pool Suppose a storage administrator responsible for an NFS server creates a share to store guest virtual machines' data. T he system administrator defines a pool on the host physical machine with the details of the share (nfs.example.com:/path/to/share should be mounted on /vm _data). When the pool is started, libvirt mounts the share on the specified directory, just as if the system administrator logged in and executed m ount nfs.exam ple.com :/path/to/share /vm data. If the pool is configured to autostart, libvirt ensures that the NFS share is mounted on the directory specified when libvir...