The Technology Chronicle

The Linked clones concept is similar to the normal VM cloning process, but with a storage saving twist ;) When we create a linked clone, a new VM is created from a base VM , at the same state. This clone with use the base VM's hard disk for all read operations, however all writes to the disk ie any change to the data from the original disk is written on  a new disk. This is very similar to the concept of snapshots where the original VMDK is read only and all subsequent writes are done to a delta disk. The main advantage of using Linked clone is to avoid deduplication of data. You can have n number of VMs created from the base virtual machine, but the base disk remains the same. This will considerably reduce the disk space usage, especially in cases like web server farms with multiple servers

VMware has released the latest version of vSphere in VMworld 2013 .Release 5.5 includes a number of significant improvements as well as new features over the past releases. Lets have a look. What is new? Application HA: The HA feature extended to applications like MSSQL,Tomcat,IIS,TC server runtime etc.It can monitor applications and take actions liek restarting the application, resetting the VM , raise an alarm or send email notifications .A vFabric Hyperic should be installed in each guest OS.Also an AppHA virtual applicance and Hyperic server is required for thsi to work Reliable memory Technology: This enables ESXi to analyze the reliability of memory ,predict failures and stop using unreliable parts of memory. It will also help put critical processes like watchdog and hostd in the reliable area.  Flash Read Cache: This was previously avaliable in Beta as vFlash. This technology leverages the local flash devices reources in a host to provide a clustered flash resources...

The hot-add and hot-plug of resources are very useful feature in vSphere where you can pile in more compute resources on the fly without a downtime for machines.Few points about this feature "Hot-add" refers to adding more memory to a VM whereas "Hot-plug" refers to adding a virtual CPU to a VM Inorder to change the hot-add/hot-plug status of a VM , the machine should be powered off i e if the feature is disabled, you should first shutdown the machine before you can enable it. This is enabled from VM settings-> options-> advanced->memory/cpu hotplug The feature is not enabled by default Minimum VM hardware version of 7 is required for hot-add/hot-plug to work. If you are using a lower version of virtual hardware, first you need to upgrade it Even if it hot add/plug enabled, for the hot add/plug to be effective, it should be supported by the VM guest operating system for the resources to be available to the VM Hot add/plug feature is not compatibl...

When we add a new disk in  a VM hosted in Vmware ESXi, we can choose whether the disk should be Independent or not. If we choose the disk to be independent, it is not included in snapshots. If you browse the datastore after taking a snapshot of the machine, you will not see any delta disks related to the independent disks. There are two types of independent disks: Persistant: The data written to the disk is retained after we powercycle the machine. It is like any normal disk that we add to a machine, only difference is that we cannot return to a point in time for data in that disk Non-persistant: Data is deleted when we powercycle the VM. I have tried it on a Windows VM and the disk is listed as unallocated space each time I powercycle the VM, thereby deleting all data saved in it. I had to initialize the disk from the disk management console and format it  as a drive before using it again. Interestingly, if we restart the windows OS the disk and the data that it contai...

The VMFS block size defines the maximum file size as well as the space occupied by a file. The following block sizes were available in vmfs 3 - 1MB, 2MB, 4 MB and 8 MB. These block sizes decided the maximum possible size of a single VMDK file that you can create for a virtual machine. The maximum disk size was limited as follows 1 MB - 256 GB 2 MB - 512 GB 4 MB - 1 TB 8 MB - 2 TB - 512 B VMFS5 offers a unified block size of 1 MB,larger blocks are not required to create disks of larger size. This means that the 1 Mb block size of vmfs 3 is not same as 1 MB  block size of vmfs 5. The maximum VMDK file size supported is 2 TB - 512 B

vSphere 5 components and features; Vmware ESXi : Well, this is the physical part of vSphere. The virtualization OS installed in  in physical servers and bastracts the physical resources of the server and distributes them across VMs. VMware vCenter : It is the vsphere centralised management software. It is essential for configuring and managing the full potential of vSphere say HA, DRS etc vSphere client: A client software that lets users connect remotely to Vmware ESXi and vCenter vSphere web client: A web interface that allows users to connect remotely to vCenter client or ESXi vSphere SDKs: Provides standard interfaces for VMware and third party solution to access VMware vSphere VMFS : A high performance cluster file systems for ESXi virtual machnes vSphere virtual SMP: Enables single virtual machine to use multiple physical processors simultaneously vMotion: Enables migration of virtual machines from one datastore to another without service interruption* vSphere HA: If the ...