HOTLINK SUPERVISOR - Heterogeneous Hypervisors – All under one Roof i.e VMware vCenter

HotLink SuperVISOR for VMware vCenter is a certified VMware Ready solution that extends the robust management capabilities of VMware vCenter to natively support all major enterprise Hypervisors — including Microsoft Hyper-V, Citrix XenServer and Red Hat Enterprise Linux (KVM).

Unlike overlay solutions that provide only basic cross-platform features on top of multiple native management toolsets, HotLink SuperVISOR abstracts the virtual infrastructure, so you can support other hypervisors utilizing the underlying capabilities of VMware vCenter. No additional management console is required — even to support advanced features like live migration and DRS!

With HotLink SuperVISOR you can:

• Manage multi-hypervisor natively with VMware vCenter!
• Clone, snapshot and migrate heterogeneous workloads
• Utilize existing templates cross-platform
• Automate any-to-any workload conversions
• Eliminate redundant native management toolsets
• Leverage existing VMware skills & investment

http://hotlink.com/technology/supervisor-vmware.html

Free edition Supports 1 Hypervisor, 3Hosts, 15 VM's. - 

A Short Video on HotLink SuperVISOR - by David Davis - from TrainSignal

IOBlazer - storage micro-benchmark tool - run in VM - brand new baby from VMware Labs

IOBlazer is a multi-platform storage stack micro-benchmark. IOBlazer runs on Linux, Windows and OSX and it is capable of generating a highly customizable workload. Parameters like IO size and pattern, burstiness (number of outstanding IOs), burst interarrival time, read vs. write mix, buffered vs. direct IO, etc., can be configured independently. IOBlazer is also capable of playing back VSCSI traces captured using vscsiStats. The performance metrics reported are throughput (in terms of both IOPS and bytes/s) and IO latency.
IOBlazer evolved from a minimalist MS SQL Server emulator which focused solely on the IO component of said workload. The original tool had limited capabilities as it was able to generate a very specific workload based on the MS SQL Server IO model (Asynchronous, Un-buffered, Gather/Scatter). IOBlazer has now a far more generic IO model, but two limitations still remain:

1. The alignment of memory accesses on 4 KB boundaries (i.e., a memory page)
2. The alignment of disk accesses on 512 B boundaries (i.e., a disk sector).

Both limitations are required by the gather/scatter and un-buffered IO models.
A very useful new feature is the capability to playback VSCSI traces captured on VMware ESX through the vscsiStats utility. This allows IOBlazer to generate a synthetic workload absolutely identical to the disk activity of a Virtual Machine, ensuring 100% experiment repeatability.


http://labs.vmware.com/flings/ioblazer

What is MultiCore Virtual CPU?

VMware multicore virtual CPU support lets you control the number of cores per virtual CPU in a virtual machine. This capability lets operating systems with socket restrictions use more of the host CPU's cores, which increases overall performance.

You can configure how the virtual CPUs are assigned in terms of sockets and cores. For example, you can configure a virtual machine with four virtual CPUs in the following ways:

* Four sockets with one core per socket
* Two sockets with two cores per socket
* One socket with four cores per socket

Using multicore virtual CPUs can be useful when you run operating systems or applications that can take
advantage of only a limited number of CPU sockets. Previously, each virtual CPU was, by default, assigned
to a single-core socket, so that the virtual machine would have as many sockets as virtual CPUs.

When you configure multicore virtual CPUs for a virtual machine, CPU hot Add/remove is disabled.
For more information about multicore CPUs, see the vSphere Resource Management Guide. You can also search the VMware KNOVA database for articles about multicore CPUs.

CAUTION You must assign a value to configuration parameter keywords. If you don't assign a value, the
keyword can return a value of 0, false, or disable, which can result in a virtual machine that cannot power on.

Prerequisites

IMPORTANT To use the VMware multicore virtual CPU feature, you must be in compliance with the
requirements of the operating system EULA.

* Verify that the virtual machine is powered off.
* Verify that you have virtual machine hardware version 7 or later.
* Verify that the total number of virtual CPUs for the virtual machine divided by the number of cores per
   socket is a positive integer.

Using MOB- (Managed Object Browser) --> Ops Panel for ESX

I was recently reading Eric Sloof article,
Where you can go and edit (index.html - which opens as ESX server home page) customize by using MOB (Via Java Scripting).. here is the cool video by Eric.

The Operations Panel is a script tool, which runs on the client browser and extends the default ESX server web page with a short list of all available virtual machines. It gives the user the ability to perform simple power operations (start, stop, suspend, resume). Easily accessible user interface for some of the most common operations on an ESX host, available directly from the ESX home page.


Ops Panel for ESX from Eric Sloof NTPRO.NL on Vimeo.

Top 10 Free vSphere ESX Tools and Utilities

Top 10 Free vSphere ESX Tools and Utilities

http://www.kendrickcoleman.com/index.php?/Tech-Blog/top-10-free-vsphere-esx-tools-and-utilities.html

What is Cloud Computing?

Cloud Computing explained - Click here for More on Cloud

What is FAST? (Fully Automated Storage Tiering) at vBlock (by VMware, EMC, Cisco)

What is FAST? (Fully Automated Storage Tiering) at vBlock
Now available for 3 Flavors (Celera, CX4, Symmetrix)

FAST approach is the Brand new at EMC,
which will automatically move the the LUNs as below..

High I/O LUN’s to Flash Drives (SSD Hdd’s)
Modest I/O LUN’s to F.C Drives
Least I/O LUN’s to SATA Drives

Here are some features, highlights of FAST and how it operates.

• FAST will perform data movement based on IOPS, average I/O size and write percentage.
This is currently true for the Symmetrix V-Max, Clariion CX4 and Celerra NS.

• Three elements that define FAST: Storage Type, FAST policies and Storage Groups.

• FAST is based on user defined -- configuration policies.

• The configuration of FAST is typically done through FAST wizards FAST LUN Migrator for Clariion CX4,
(Symmetrix Management Console) on Symmetrix V-Max and Rainfinity File Management Appliance or VE for Celerra NS.

NOTE: Out of the box thinking by EMC, imagine the flexibility one would have
with a large infrastructure and FAST moving data based on policy.
It’s all about the big picture.

FAST – EMC Hands on Demo



Source : www.storagenerve.com (Full Article Link below)

http://storagenerve.com/tag/vblock/

VMware vCenter Mobile Access (vCMA) - Allow to Manage Vsphere Infrastructure from Mobie.. Yes, You heard it Right!

VMware vCenter Mobile Access (vCMA) - vCMA allows you to monitor and manage VMware Infrastructure from your mobile phone with an interface that is optimized for such devices. Specifically, it allows you to:

• Search for virtual machines in your data center
• Migrate virtual machines from one host to another using vMotion
• Execute recovery plans using VMware Site Recovery Manager
• Access Scheduled Tasks, Alarms and Events

And much more..



Installation Procedure & Packaging

The vCenter Mobile Access server is packaged as a virtual appliance. The username/password on the appliance is root/vmware but console access should not be required. The root password should be changed after install.

Download the vCMA OVF distribution zip file from this link (the file is approximately 350 megabytes). The zip file contains the appliance OVF file and other system files.


Follow these steps to install the Mobile Access appliance:

1. Extract the zip file to a temporary directory, for example c:\temp. The files contained in the zip file include :
* vCenterMobileAccess-1.x.y.z.ovf
* system.vmdk
2. Launch the VI Client and log into your ESX box or vCenter instance.
3. In the inventory view, select the menu File-> Virtual Appliance -> Import…
4. Select the option “Import from file:” and browse to the OVF file, for example: c:\temp\vCenterMobileAccess-ovf\vCenterMobileAccess-1.0.0.10.ovf and follow the wizard next steps.
5. In the “End User License Agreement” page, read the license agreement completely and click on the “Accept all license agreements” and continue the steps.
6. In the “Name and Location” page, provide the name for your Virtual Machine.
7. Once the wizard completes, a virtual machine will be created. Select the virtual machine and power it on.

Open your local browser (http://IP Address of vCMA:5480)

On your mobile http:///vim

Once connected, you will see the login screen where you can provide the vCenter or ESX IP address or name as well as username and password.

Feature Compare vSwitch 3.5, vSwitch 4.0, dVswitch 4.0, Cisco Nexus 1000

The following Table is a list of the key features of VMware vNetwork Distributed Switch. For a comprehensive list of VMware vSphere features download the key features summary.

Simplify and Enhance Virtual Machine Networking

• Simplified provisioning and administration of virtual networking across many hosts and clusters through a centralized interface.
• Simplified end-to-end physical and virtual network management through third-party virtual switch extensions for the Cisco Nexus 1000V virtual switch.
• Enhanced provisioning and traffic management capabilities through private VLAN support and bi-directional virtual machine rate-limiting.
• Enhanced security and monitoring for virtual machines migrated via VMware VMotion through maintenance and migration of port runtime state.

Click below --> Read More for Full Article..

Load-balancing Methods (I prefer to call Teaming Methods) --> 1) Originating Port ID Based 2) MAC Hash Based 3) IP Hash Based - Which is best, in real & what supports Actual Load Balance????

Now that we understand the basics, we will move on to the topic at hand, NIC Teaming. Although you can team vNIC's within a VM, we are not going to discuss OS vNIC teaming, but rather physical NIC teaming. You may be wondering why someone would want to team physical NIC's? Well why not! Teaming the NIC's will not only eliminate the single point of failure associated with a single physical NIC, but also provide better overall network throughput - what's not to like!?!

ESX offers 3 different methods for load balancing. However, not all methods are created equal, and only one method offers true load distribution. The 3 load-balancing methods include:

• Route based on the originating port ID (this is the default if not defined otherwise) - Also know as vSwitch port-based load-balancing, this method chooses an uplink based on the virtual port where the traffic entered the virtual switch.

• Route based on source MAC hash - This method chooses an uplink based on a hash of the source Ethernet address.

• Route based on IP hash - This method chooses an uplink based on a hash of the source and destination IP address of each packet.

Click below --> Read More for Full Article (Which one will give Real Load Balancing)

Cool new HA feature coming up to prevent a split brain situation! in ESX 4 Update 2

Source - www.yellow-bricks.com

One of the most common issues experienced with VMware HA is a split brain situation. Although currently undocumented, vSphere has a detection mechanism for these situations. Even more important the upcoming release ESX 4.0 Update 2 will also automatically prevent Split Brain of H.A!

First let me explain what a split brain scenario is, lets start with describing the situation which is most commonly encountered:

4 Hosts – iSCSI / NFS based storage – Isolation response: leave powered on

When one of the hosts is completely isolated, including the Storage Network, the following will happen:
Host ESX001 is completely isolated including the storage network(remember iSCSI/NFS based storage!) but the VMs will not be powered off because the isolation response is set to “leave powered on”. After 15 seconds the remaining, non isolated, hosts will try to restart the VMs. Because of the fact that the iSCSI/NFS network is also isolated the lock on the VMDK will time out and the remaining hosts will be able to boot up the VMs. When ESX001 returns from isolation it will still have the VMX Processes running in memory. This is when you will see a “ping-pong” effect within vCenter, in other words VMs flipping back and forth between ESX001 and any of the other hosts.

As of version 4.0 ESX(i) detects that the lock on the VMDK has been lost and issues a question if the VM should be powered off or not. Please note that you will(currently) only see this question if you directly connect to the ESX host. Below you can find a screenshot of this question.



With ESX 4 update 2 the question will be auto-answered though and the VM will be powered off to avoid the ping-pong effect and a split brain scenario! How cool is that…

VMware ThinApp (Formerly Thinstall) - Application Virtualization

VMware ThinApp (formerly Thinstall) is an application virtualization and portable application creator suite by VMware  that can package conventional applications so that they become portable applications.

Ex   :  Ms-Office is Conventional App - Requires Installation & Registry updates, 
Ex   :  Putty.exe is Portable App - Portable app runs anywhere without actual 
          installation (may be from pen drive as well)
          
          To make a straight cut, ThinApp will emulate  Conventional Apps to 
          Portable Apps

VMware ThinApp is an application virtualization solution ThinApp is able to execute applications without them being installed in the traditional sense by virtualizing resources such as environment variables, files and Windows Registry keys. The virtual environment presented to the client is a merged view of the underlying physical and virtual resources, thereby allowing the virtualization layer to fool the application into thinking that it is running as if it were fully installed.

ThinApp Video Demo by VMware

All about VMware Data Recovery - Read on - Dont miss the video

VDR  - VMware Data Recovery (My understanding as below)

What is VDR

VDR is a Backup & Recovery Appliance - Customized on Cent OS

(available from VMware as an OVF - Open Virtualization format)

You can download .OVF file & install from vSphere Client

(VM will be created automatically attached to your chosen Phy.ESX Host) 

You can install VDR Plug-ins and execute Backup & Restore directly from vCenter, on any level of Infrastructure (entire Datacenter, Cluster or VM level)

 Click below --> "Read More" for Full Article (Why VDR, Why not VDR & Demo Video)..

Xsigo - I/O Virtualization - How VMware & VMware customers can benefit on this (of course other OS also can benefit - Below video on VMware)

 *Disclaimer - (content sources are from public display of respective of vendors)

Xsigo will enables you to have a single 20 Gbps I/O Card on Server

(which provides Virtual NIC, V FC HBA, V iSCSI HBA or any legacy I/O Card) to OS. Hence users need not have look for Physical Compatible slots, cards and additional cabling on server rack.. That's awesome - we don't need to open Server, not required to make make your hands dirty, no downtime negotiations with stake holders - everything is on-the-fly (while OS is up & running - I can present any virtual PCI Card to OS) - today Project requirement is SCSI, tomorrow iSCSI, then FC, then FCOE - don't worry - one Xsigo Card will provide any virtual PCI card to OS.

One card and one cable will be connected to VP780 I/O Director - which provides Virtually every Card to Server.. You may read more about this @ below link.. 
Good news is  --> Gaint OEM vendor "Dell" is Xsigo Partner as well

http://www.xsigo.com/products/products_overview.php

I made a small Presentation on Xsigo, you may take a look at it - Click to download

VMDirectPath (ESX 4 Onwards it's mostly on GUI --> Configuration Examples and Troubleshooting

Now working with Tape Drives, Libraries & 10Gbps devices,
direct from VM's (not from ESX) is piece of cake..

VMware made it more easier through GUI - you don't need to make your hands dirty by editing .VMX.

However, be prepared for few special cases - need to edit .VMX again.

Configuring VMDirectPath I/O pass-through devices on an ESX host - Extract from VMware KB - 1010789 - Click this for link

Purpose

This article provides steps for configuring VMDirectPath I/O direct PCI device connections for virtual machines running on Intel Weybridge and Stoakley platforms.

Resolution

About VMDirectPath I/O pass-through devices

You can connect up to two passthrough devices to a virtual machine. When selecting the devices, keep in mind these restrictions:

• Devices cannot be plugged in after a PCI Bridge.
  
  
• You cannot have two devices in two different contexts (for example, one used by VMkernel and one in pass-through) using the same PCI slot. For example, the dual head NIC is dedicated to the VMkernel OR is available for pass-through. If you select one, the other is automatically selected as well. A dialog informs you why this occurred.

Configuring pass-through devices

To configure pass-through devices on an ESX host:

1. Select an ESX host from the Inventory panel of VMware Infrastructure (VI) Client.
2. On the Configuration tab, click Advanced Settings. The Pass-through Configuration page lists all available pass-through devices.
   
   Note: A green icon indicates that a device is enabled and active. An orange icon indicates that the state of the device has changed and the host must be rebooted before the device can be used.
   
   
3. Click Edit.
4. Select the devices and click OK.
   
   Note: If you have a chipset with VT-d, when you click Advanced Settings in VI Client, you can select what devices are dedicated to the VMDirectPath I/O.
   
5. When the devices are selected, they are marked with an orange icon. Reboot for the change to take effect. After rebooting, the devices are marked with a green icon and are enabled.
   
   Note: The configuration changes are saved in the /etc/vmware/esx.conf file. The parent PCI bridge, and if two devices are under the same PCI bridge, only one entry is recorded.
   The PCI slot number where the device was connected is 00:0b:0. It is recorded as:
   
   /device/000:11.0/owner = "passthru"
   
   Note: 0b is 11 in decimal.

To configure a PCI device on a virtual machine:

1. From the Inventory in VI Client, right-click the virtual machine and choose Edit Settings.
2. Click the Hardware tab.
3. Click Add.
4. Choose the PCI Device.
5. Click Next.
   
   Note: When the device is assigned, the virtual machine must have a memory reservation for the full configured memory size.

Additional Information

For related information, see the VMDirectPath Tech Note at http://www.vmware.com/pdf/vsp_4_vmdirectpath_host.pdf.

VMDirectPath or SCSI Passthru - Making SCSI Card & Devices available to VM's on ESX 3.5.x onwards

Configuring tape drives and media changers on ESX 3.x

Making SCSI Card & Devices available to VM's on ESX 3.5.x onwards (PassThruSCSI)

So that VM (Guest OS) can access SCSI Card & Tape Drives / Medium Changers to fire Backup or Restore (directly from VM) -Currently OEM vendors are not supporting officially - But VMware supports

Details

This article provides instructions for configuring tape drives and media changers so that the virtual machines on ESX 3.x hosts can access the devices. 

Note: Fibre channel attached tape drives are not supported in ESX. For more information, see the SAN System Design and Deployment Guide.

Solution

(VMware KB Article- Click to visit KB

Why should we call VMware will "Optimally utilize the Infrastrusture Resources" - Series1 - Keep your tab on this for my next Series

1) Memory Baloon Driver - Vmmemctl:

(My Understanding in other words - below)

Freeing up the non frequently used / less significant Memory Pages by inflating Vmmemctl Baloon Intentionally creating shortage of memory in specific VM, so that those non frequent Memory Pages Are pushed to Swap file and freed up Memory is under Common Pool (by Vmkernel control - can be shared to other VM's). Once Vmkernel is having enough Memory space and no application is Memory crunch, automatically Vmmemctl Baloon is Deflated, Specific VM has got back it's respective memory.. Very cool feature, 65% of specific VM memory can be freed up by Vmware by default by inflating this Vmmemctl Baloon Technique, However Admin can configure 0%-75% Vmmemctl baloon

Memory Balloon (vmmemctl) Driver

(Extract of VMware Online Library - below)

The vmmemctl driver collaborates with the server to reclaim pages that are considered least valuable by the guest operating system. The driver uses a proprietary ballooning technique that provides predictable performance which closely matches the behavior of a native system under similar memory constraints. This technique effectively increases or decreases memory pressure on the guest operating system, causing the guest to invoke its own native memory management algorithms. When memory is tight, the guest operating system decides which particular pages to reclaim and, if necessary, swaps them to its own virtual disk.

Figure 9-3. Memory Ballooning

Note: You must configure the guest operating system with sufficient swap space. Some guest operating systems have additional limitations. See Swap Space and Guest Operating Systems.

If necessary, you can limit the amount of memory vmmemctl reclaims by setting the sched.mem.maxmemctl parameter for a specific virtual machine. This option specifies the maximum amount of memory that can be reclaimed from a virtual machine in megabytes (MB). See Setting Advanced Virtual Machine Attributes.

2)Transparent Memory Page Sharing

Transparent page sharing is a cool feature of ESX Server that allows VMs to share memory pages that have identical content. If a VM needs to modify the shared data, then the VMkernel creates a new copy for the VM that it can modify. The Operating Systems are not aware that they are sharing memory with other VMs (hence, the name - Transparent page sharing implies)

My Understanding : VM kernel will keep monitoring all VM's Memory Pages and eliminates to occupy the space for redundant copies among various Memory Pages - Instead maintain one copy of common Memory Page ( rest of VM's will have pointer towards this)

VMware vSphere 4 Guided Consolidation

I have added VMware Mylearn Demo Link (Click this Link) - for Guided Consolidation Demo

 (Doesn't work If Pop Up Blocker is there)

Article Extract From : Whugh Griffin Word Press   (Below)

Guided Consolidation is a tool that will allow you to monitor a physical computer and determine it’s potential for adding to your virtual environment. I would highly recommend it for a small to mid sized business looking for some assistance with their P2V process. It has an easy to use interface with a more simplified approach than using the full VMware Capacity Planner utility.
It is free and can be installed from the vCenter installation CD. Once installed, it can be accessed from the vCenter Home Menu. In order to scan a physical computer, you will need to make sure the credentials provided during installation must have administrative permissions on any remote Windows systems selected for analysis. This user account supplied during installation is used to run the “VMware vCenter Collector Service”, a Windows service used to connect to the remote systems.
Once the tool begins to scan the system, it will gather data and display CPU information and utilization, memory information and utilization as well as the computer name. Sometimes it may take up to 1hr before this process begins. Be prepared to allow 24 to 48hrs for this process to complete as Guided Consolidation builds a confidence metric level. Once a high enough confidence level is reached, the status of the system changes to “Ready for consolidation”.
At this point, a consolidation plan is available by selecting the analyzed computer and clicking the “Plan Consolidation” button.
This plan will include a star rating which will identify how likely the physical computer is for virtualization and will even make a recommendation for the target host. The rating system ranges from 1 to 5 stars, with 5 stars indicating the system is a high candidate for the proposed host. From the Consolidation Wizard, you can change several things, the name of the VM, the host being assigned too or even remove a VM altogether from the list.
Multiple systems can be converted to VM’s using this wizard, it’s a very simple process and by the click of one button you are off to the races converting your physical systems to virtual machines.
***Keep in mind that before using Guided Consolidation that a datacenter exists and a host is added to the vCenter Server inventory. ***
I would highly recommend looking at this pdf: http://www.vmware.com/pdf/vsphere4/r40/vsp_40_admin_guide.pdf or picking up a copy of Mastering VMware vSphere 4 by Scott Lowe for more in-depth information on Guided Consolidation.
I hope this gives you a basic understanding of how Guided Consolidation can help you plan a smooth P2V process.

Fault Tolerance (FT) Implementation Checklist & Validation Tool (Site Survey Tool from VMware)

Here is the F.T Checklist (very handy) to get started with instant Implementations..


F.T is next level of H.A in vSphere
HA will power on the VM (causes reboot from beginning) on 2nd ESX host incase of 1st ESX (Native host of that VM) Fails..

But F.T will keep track of Memory changes on Primary ESX and keep replicating to to Secondary ESX Host (VM Memory - Standby) always. (LockStep Mechanism - Actually Vmware follows internally Record & Play Technology - inherited from VMware Player)  In case of 1st ESX Fails, same VM is instantly attached to 2nd ESX host (Completely Zero Downtime – Yeah, you heard it right, Zero downtime was not possible in HA)

I am excited to read between these lines & to implement this..

FT Check List --> http://ntpro.nl/blog/archives/1090-Fault-Tolerance-Checklist.html

In spite of having checklist verified, you my overlook a few..
Here is the trick of my sleeve, Just download and run the “Site Survey Tool” from VMware Shared utilities to validate F.T pre-requisites..

Provide your vCenter (IP / Hostname) --> as prompted by Site Survey Tool --> Select your Cluster in vCenter to run F.T Validations on your cluster

Tool will validate Proc Specs, Shared Storage, Thick Disk is there or not, Snapshot should not be in VM, more than single vCPU should not be there in VM and lot more..

Leave it tool to check it for you, post to which you may correct problems
(or else ensure to follow the F.T Checklist (link here) minimize issues)

Site Survey Tool Download link --> http://www.vmware.com/download/shared_utilities.html

Virtual Distributed Switch and vCenter Server failure

Virtual Distributed Switch and vCenter Server failure

What happens to ESX hosts Network Traffic(Incase of dVswitch Fails / Vcenter is down)

Dont miss out the last paragraph of this post

I’m currently working with my colleagues on an upgrade of our VI 3.5 infrastructure to vSphere Enterprise Plus. We have recently been mulling over some of the design elements we will have to consider and one of the ones that came up was virtual Distributed Switches (vDS). We like the look of it, it saves us having to configure multiple hosts with standard vSwitches and it also has some nice benefits such as enhanced network vMotion support, inbound and outbound traffic shaping and Private VLANs.

One of the questions that struck me was, what happens if your vCenter server fails? what happens to your networking configuration? Surely your vCenter server couldn’t be a single point of failure for your virtual networking, could it?

Well I did a bit of digging about, chatted to a few people on twitter and the answer is no it would not result in a loss of virtual networking. In vSphere vDS the switch is split into two distinct elements, the control plane and the data plane. Previously both elements were host based and configured as such through connection to the host, either directly using the VI client or through vCenter. In vSphere because the control plane and data plane have been separated, the control plane is now managed using vCenter only and the data plane remains host based. Hence when your vCenter server fails the data plane is still active as it’s host based where as the control plane is unavailable as it’s vCenter based.

Mike Laverick over at RTFM informed me that the central config for a vDS is stored on shared VMFS within a folder called the .dvsData folder. I’ve since learnt that this location is chosen automatically by vCenter and you can use the net-dvs command to determine that location. It will generally be on shared storage that all ESX hosts participating in the vDS have access to. As a back up to this .dvsData folder a local database copy is located in /etc/vmware/dvsData.db which I imagine only comes into play if your vCenter server goes down or if your ESX host loses connectivity to the shared VMFS with the .dvsData folder. You can read more about this over at RTFM