In my last post Storage Design Considerations- Overview I have discussed few points that are very crucial and must be paid serious attention while designing the storage infrastructure.

In this post I will discuss about the importance of the availability of the storage component in a virtual infrastructure and important considerations:

Availability of the storage component is very crucial. No vSphere or SAN admin will ever want to face a situation of complete outage from storage point of view.

Performance and Capacity issues are not that much disruptive and if very well planned and monitored then those issues can be rectified without any downtime.

To avoid situation of complete outage we should build redundancy on each and every components of the storage devices. All your physical servers can be connected to a one large piece of storage device and failure of it means a situation of chaos for you. So every components and connections have sufficient levels of redundancy to ensure that there are no single points of failure

Whenever we talk about availability we always talk about the concept of the 9’s.… Read More

Storage is perhaps one of the most critical piece in any virtualized environment. All the virtual workloads in a small or large environment is running on some sort of storage. It may be either local disks present in a server or can be cheap NAS devices or the expensive SAN devices.

A lot of innovation is going on in storage technology and it’s kinda fueled by the capabilities which are induced in the new hardware versions of the devices. Storage is just not about how much space you are getting against every dollar invested. The advancements in virtualization has affected storage seriously and it is now much more than just capacity.

Due to this reason the vSphere 5.0 release is also known as storage release sometimes. Features such as Storage vMotion help abstract not just the server hardware but also the storage. Storage DRS and Profile Driven Storage features has allowed the admins to get more value from the expenditure made on storage.… Read More

These days it has become hard to keep track of all VMware’s Product Launches, upgrades, hotfixes and new releases.

To make things simpler VMware launched a new program called VMware Software Manager, that can help you track which is the most recent release of its products and more, download them while checking the integrity of them. It is a free product that dramatically simplifies the download of VMware suites and products.

VMware Download Manager was announced at the same time when vSphere 6.0 was announced and it is still in its early phase (version 1.0) and the download catalog is currently limited to the following Datacenter and Cloud infrastructure products:

• VMware vCloud Suite 6.0, 5.8, and 5.5
• VMware vSphere w/ Operations Management 6.0 and 5.5
• VMware vSphere 6.0, 5.5, and 5.1

Advantage of using Software manager over general downloading method:

Easy to Use

Provides an easy to use interface to find, select & download the content needed to install or upgrade a VMware suite with the push of a button

File Integrity Check

Verifies the suite was downloaded without corruption

New Release Detection

Automatically detects the release of new VMware suites, products and versions

System Requirements

To be able to install and use Download Service, you must ensure that your system meets specific operating system and Web browser requirements.… Read More

Deleting virtual machine snapshots without wasting disk space

Before using snapshots on your VM, analyzing free disk space on the VMFS volume is very important.  As a best practice or thumb rule you should have least 20% of the virtual machine’s total disk size as free disk space before using snapshots. But this amount can vary depending upon the type of server or how long you will keep the snapshots or if you are planning to use multiple snapshots.

If you are planning to use snapshots on servers like database servers or file servers the amount of free space that should be present on underlying datastore or VMFS volume will change drastically as comparison to using snapshots on servers like web servers or say DNS server because the amount of data written on disks in case of file or database server is much more than any other type of servers.

More importantly if you are planning to include the memory state of the VM’s with snapshots, you’ll also need to allow for extra disk space equal to amount of RAM assigned to the VM.… Read More

What is a Snapshot

We have heard this term time and again during our journey with working on VMware and many of us are aware of what it is. Still I am including the formal definition of snapshot as below:

Disk Snapshot in VMware refers to a copy of the virtual machine disk file at a certain point in time. It preserves the disk file system and system memory of your virtual machine by enabling you to revert to the snapshot in case something goes wrong.

Snapshots are very helpful in the cases when you are planning to upgrade or patch your mission critical applications and servers.

When a snapshot is taken on a VM then a new disk file by the name *–delta.vmdk is created in the same folder where VM disks are residing (Unless and until you are not using WorkingDir parameter)

All the write operations are freeze on the original vmdk disk present in your VM and the new write operations will be performed on the newly created delta disk.… Read More

Virtual MAC address assignments are based on Microsoft’s organizationally unique identifier (OUI) registration with the Institute for Electrical and Electronic Engineers (IEEE). An OUI is a unique MAC address prefix assigned that is assigned to all NIC vendors, both physical and virtual.

VMware Organizationally Unique Identifier (OUI) allocation uses the default OUI 00:50:56 as the first three bytes of the MAC address generated for each virtual network. The MAC address-generation algorithm produces the rest of the MAC address. The algorithm guarantees unique MAC addresses within a virtual machine and attempts to provide unique MAC addresses across virtual machines.

The VMware Universally Unique Identifier (UUID) generates MAC addresses that are checked for conflicts. The generated MAC addresses are created by using three parts: the VMware OUI, the SMBIOS UUID for the physical ESXi machine, and a hash based on the name of the entity that the MAC address is being generated for.… Read More

svMotion is fair simple process and nothing much complex is involved in that. Here are the step by step breakdown of what happens in background of svMotion process:

1. The virtual machine working directory is copied by VPXA to the destination datastore.
2. A “shadow” virtual machine is started on the destination datastore using the copied files. The “shadow” virtual machine idles, waiting for the copying of the virtual machine disk file(s) to complete.
3. Storage vMotion enables the Storage vMotion Mirror driver to mirror writes of already copied blocks to the destination.
4. In a single pass, a copy of the virtual machine disk file(s) is completed to the target datastore while mirroring I/O.
5. Storage vMotion invokes a Fast Suspend and Resume of the virtual machine (similar to vMotion) to transfer the running virtual machine over to the idling shadow virtual machine.
6. After the Fast Suspend and Resume completes, the old home directory and virtual machine disk files are deleted from the source datastore.

… Read More