How to set round robin path and multipath policy for datastore in VMware


This Article will let you know How to set round robin multipath policy for Data Store in VMware

What is Multipath policy in storage: It means that your LUN is coming from different storage switches which are coming from different zoning for redundancy purpose.



What is round robin path policy: This is an algorithm which is used to manage path which are currently available in active state. Here in above diagram where we have one storage device that is connected two switches, both are having two ports.
We have two SAN switches that are connected from Storage Port 1, Port 2 and these are further connected with physical server that is having  HBA Cards.
In Virtual environment if Storage team provides you a LUN, then only the two active paths in this datastore will be visible. Actually the fabric switches are configured with “Zoning”.


In VMware Multipath is used to provide redundancy on datastore.


VMware is having 3 Multipath Policy: a) Most Recently Used b) Round Robin c) Fixed

Most Recently Used (MRU): In this Policy ESXi use first working path and if first path is not available then it goes to next path. This will not return to first path until unless path is not available. These LUN’s coming from Active/Passive Storage array.
Fixed (Fixed): In this policy ESXi use only assigned path only, else this will start using first working path which was discovered at boot time. In this policy host automatically returns to first path when it will be available. These LUN’s is Active/Active Storage array example.
Round Robin (RR): In this policy ESXi use Automatic path selection and use all available paths by rotationally. It helps us in distributing load across the configured paths. Recommendation is to use this RR policy in your environment for all Data stores to get better performance and redundancy.



We can make Data Store Round Robin in two ways:   1. Script 2. Manually

 1st Method-> Script:
Here is the script you have to run this script on vCenter Server.
Log in into vCenter server and open power shell and provide the script path and enter. Rest script will do but before that you have to save as this script with extension .ps1



# Set pathing policy to RoundRobin

Get-Cluster “Here Cluster name” | Get-VMHost | Get-ScsiLun -CanonicalName “naa.*” | Set-ScsiLun -MultipathPolicy


Below Script can be use for getting default storage path policy on particular ESXi Server .

# Check default pathing policy on host

Get-VMHost “Hostname (FQDN)” | ForEach-Object {

$esxcli = Get-EsxCli -VMHost $_



Below Script can be use for setting storage path policy to Round Robin on particular ESXi Server.

# Set default pathing policy for single host

Get-VMHost “Hostname (FQDN)” | ForEach-Object {

$esxcli = Get-EsxCli -VMHost $_



Below Script can be use for setting storage path policy default to Round Robin on particular cluster .

# Set default pathing policy for all hosts in Cluster

Get-Cluster “Cluster Name” | Get-VMHost | ForEach-Object {

$esxcli = Get-EsxCli -VMHost $_




 2nd Method-> Manually 
 Log in vCenter and then Select Host and click on one host> configuration tab > storage > click on one data store > properties > manage paths > and check path selection > here select Round robin and click on change then click on close.




What is Virtual SAN (VSAN) Software Defined Storage

This Article describes you about What is Virtual SAN (VSAN) Software Defined Storage



VMware introduce Virtual SAN that is a new software-defined storage solution and fully integrated with vSphere. Virtual SAN is locally attached disks in a vSphere cluster to create a storage solution that rapidly can be provisioned from VMware vCenter during virtual machine provisioning operations.

It’s a solution in which storage and compute for virtual machines are combined into a single device, with storage’s being provided within the hypervisor itself.

This will provide central storage for Virtual machine and capabilities through a SPBM platform. SPBM and virtual machine storage policies this simplifies virtual machine storage placement decisions for vSphere administrators.

Virtual SAN is fully integrated with core vSphere enterprise features such as VMware vSphere High Availability (vSphere HA), VMware vSphere Distributed Resource Scheduler (vSphere DRS), and VMware vSphere vMotion. This provided high availability and scale-out storage functionality both. It also can be considered in the context of quality of service (QoS) because virtual machine storage policies can be created to define the levels of performance and availability required on a pervirtual machine basis.


Virtual SAN can scale out to 32 hosts


Managed via vCenter Server


Virtual SAN requires a vCenter Server running 5.5 Update 1 or higher. Virtual SAN can be managed by both the Windows version of vCenter Server and the vCenter Server Appliance (VCSA). Virtual SAN is configured and monitored via the vSphere Web Client and this also needs to be version 5.5 Update 1 or higher.


 Requirement to configure VSAN


Here you require at least 3 vSphere hosts for creating Virtual SAN each host should be local storage. in order to form a supported Virtual SAN cluster.

It allow host failure tolerance (one host) to the cluster so that it can meet the minimum availability. Basic requirement is that the vSphere hosts must be running vSphere version 5.5 Update 1 at a minimum. Note: if you are running with fewer hosts then there will be a risk to the availability of virtual machines if a single host goes down. The maximum number of hosts supported is 32.

Each vSphere host in the cluster that contributes local storage to Virtual SAN must have at least one hard disk drive (HDD) and at least one solid state disk drive (SSD).




  • A SAS/SATA Controller (Storage Controller in “pass-through” or RAID0” mode) is required
  • A combination of HDD & SSD devices are required (a minimum of 1 HDD & 1 SSD [SAS or SATA]), although we expect SSDs to make up 10% of total storage
  • The SSD will provide both a write buffer and a read cache. The more SSD capacity in the host, the greater the performance since more I/O can be cached.
  • Not every node in a Virtual SAN cluster needs to have local storage. Hosts with no local storage can still leverage distributed datastore. However, the recommendation is to have hosts similarly configured, for optimal resource utilization balancing.
  • Each vSphere host must have at least one network interface card (NIC). The NIC must be 1Gb capable. However,as a best practice, VMware is recommending 10Gb network interface cards.
  • A Distributed Switch can be optionally configured between all hosts in the Virtual SAN cluster, although VMware Standard Switches (VSS) will also work.
  • A Virtual SAN VMkernel port must be configured for each host. With a Distributed Switch, NIOC can also be enabled to dedicate bandwidth to the Virtual SAN network.


The VMkernel port is labeled Virtual SAN. This port is used for inter-cluster node communication and also for read and writes when one of the vSphere hosts in the cluster owns a particular virtual machine, but the actual data blocks making up the virtual machine files are located on a different vSphere host in the cluster. In this case, I/O will need to traverse the network configured between the hosts in the cluster.


How to configure:
1. First open VMware vSphere WebClient.


2. Select Home tab> Double-Click Hosts & Clusters


3. Expand the navigation on the left side and click vCenter


4. With ESXi selected navigate to Manage -> Networking -> VMkernel adapters


5. You must now add a VMkernel adapter for the Virtual SAN traffic. Click the icon to add a new adapter.


6. Select VMkernel Network Adapter. Click Next


7. We have already attached each host to a distributed switch and created a VSAN port group. You must select the port group to use for this host. Click Browse

8. Select the VSAN Network and click ‘OK’.

9. Keep the default settings but select Virtual SAN traffic. Click Next


10. Keep the default settings. Click Next


11. Click Finish if your screen looks like the above


 12. You should now see vsan added for the VSAN Network. Now Enable Virtual SAN


 13. Once your network adapters are in place we can turn on Virtual SAN at the Cluster level.
 Select Cluster Site then navigate to Manage> Settings> Virtual SAN> General > Edit

14. Check “Turn ON Virtual SAN”, click OK. I am going to keep “Manual” selected for this lab. The Automatic option will add all empty disks on the hosts to be claimed by Virtual SAN.


15. Create Disk Group for Virtual SAN. From here we will create a new disk group that will use all eligible disks. Select Cluster Site> Manage > Settings > Virtual SAN > Disk Management > Claim Disks (disk number)


16. Click “Select all eligible disks”


17. All hosts and disks should now be selected. Click “OK”.


How to Create a SAN Certificate for citrix


This article will let you know that How to Create a SAN Certificate for IIS server or Storefront (Citrix) server.

1. On the server where this certificate requires, run ‘CMD.EXE’ as an administrator.
2. Run the MMC Snap-In
3. Add Certificate Services, to the local machine
4. Create a custom request

5. Here you have to Proceed without an enrolment policy

6. Choose the following settings as shown in below pic

7. Here you have to click on Select Properties

8. Add the friendly name (i.e. Citrix or Server name with date)

9. Add the DNS Names required for the certificate. It’s important here to add the DNS name of the server as well as the alternative names in case primary server down then secondary DNS server can reply.

10. Choose the certificate Common Name

11. Now you have to Add details for the Key Usage

12. Add details for the extended Key Usage

Now your certificate is ready. The request file should be saved, and the request completed on the Certificates server





How to check Virtual Machine (VM) freeze logs in VMware


This article guide you How to check Virtual Machine (VM) freeze logs in VMware


a) SSH should be enable/running for that Host.


1. Open the putty.


2. Connect to ESXi host on which your virtual machine is residing (You can connect to any ESXI host which is same VMware cluster in which your Virtual machine is residing. But the SSH service of the ESXi host must be in running state). Click on open.


3. Enter the root credential which was supplied at the installation time.

4. Then type find . –name vmname.vmx and enter.

5. Then type CD the path which got apart from the name which we were searching.
6. Then make sure vmware.log if it existing on the location bu using ls -l.

7. Then run grep| “Checkpoint_Unstun: vm stopped for” vmware.log in addition you can use |less so sceen will move slowly.

8. If you are getting the below result it is confirming VM is getting freeze.

Note: In this example, the virtual machine was stunned for 1098094 microseconds (1 second = 1 million microseconds).

Create a Network Load Balancing Cluster (NLB)

This article will let you know that how to Create a Network Load Balancing Cluster for your Terminal servers or Storefront Servers.


What is NLB (Network Load Balancing)?


Network load balancing distributes the traffic load between members of NLB servers through which come through TCP/IP.
The best example where we can use is Jump box and Citrix Storefront etc.
(Jump Server – they are the servers from which we can do RDP of servers to manage devices in a separate security zone or within the same zone)


 This is basically used in big environment where your users login frequency is high. This will help to them to serve in a better way.
  1. NLB support 32 servers in a single cluster
  2. You can add Host to NLB cluster without bringing down the cluster vice versa for deletion hosts
  3. Detect and recover host that fails or goes offline.
  4. Automatically load the balance when you add hosts or remove
  5. Within 10 seconds it can redistribute and recover the load
Easy to manage: You can manage or add servers from a single server through NLB manager.



Prerequisites for NLB setup

  1. Two or more server.

  2. Two Network adaptor ( you can configure with one adaptor but it’s best practice)

  3. Use only TCP/IP

  4. Serve should be in domain

  5. All the servers which you want to add in this NLB should have Network Load balancing Features installed


Installation Steps:
1. Login into server and open Server Manager and go to Features

2. After that it will show you the entire features list.

3. Here you have to select Network Load Balancing and click next.

4. After that it will show you summary and click on install.

5. After that go to Start Menu and open Administrative Tools and here you will see one option Network Load Balancing Manager click on this and procedure further.


6. Here you will see Network Load Balancing Manager Console. Right click and click on New Cluster option.


7. Here you have to provide Your Second Server IP or name (FQDN) which you want to add. Here you will see two NIC/IP details which are existing on that server. Select the NIC which you want to use for NLB.


8. After selection you see IP and Subnet IP, click next.


9. Here you have to provide Cluster IP Address Click on add.

10. Here you have to provide IP for cluster, Full internet name and cluster operation mode.


11. If you want to configure Port rules then click edit and do the same.


12. Here you will see your server

Patching ESXi with VMware Update Manager

To Keep you environment Up-to-date and Risk free


What is Update manager: 
It allows you to manage automatic patch and version management for ESXi Hosts, Virtual machine hardware, VMware tools and Appliances as well.
You can install Patches for these (components) through single console, easy to manage.
It will also help you to keep you infra up to date with latest patches, Hotfix and reduce vulnerabilities. Also low your security breaches risk.


Update manager can perform below tasks:
  1. It can scan the infra for checking compliance and apply the updates on selected Hosts, Virtual appliance and also on Virtual Machine Hardware to update them with selected updated or version.
  2. It can also update third party software’s on hosts as well.
  3. It can upgrade Hosts directly from previous version to new one.
  4. It can ( 5.1 update manager) update Hosts: ESXi 4.x and 5.x version.


Note:  A Host which is upgraded or migrated from lower version to higher version will not be roll back to old version. To avoid this you should backup your Hosts configurations before any activity so that you can restore to old state.

How to do patching with Update Manager


 1. Open VCenter and go to Update Manager


2. After that you have to create baseline first

3. A dialog box will be visible here you have to provide Name for this base line. Also select base line type : like a) Host Patch b) Host Extension c) Host Upgrade or if you want to upgrade your virtual appliance then select VA Up grade.


4. On the next page you will see Patch Options: Fixed and Dynamic

Recommendation: Always use “Fixed” option for your environment. Dynamic is used in that situation where you have installed New ESXi and want to update all updated which was release till date.

5. Here you have to select which patch you want to install. Select that patch and click on down arrow.


6. Ready to complete page will show you summary


7. After creation you will see this base line in Baseline and Groups tab.
 Then you have to go to vCenter > host and cluster. Select Host and go to update manager Tab


8. Then go to Attach > 9. select the patch Baseline

9. Then you have to scan and get the host status as Non-Compliant or incompatible or compliant.
10. After that you have to click on Stage > this will copy or put all the patches on host repository
11. After that click on Remediate > this will install all the patches to that host.




Need to put Hosts into Maintenance Mode
Before starting remediate a host needs to be in Maintenance Mode. This ensures that no live virtual machines are running on the system, they have either been vmotion onto other hosts or powered down. The remediation task is able to put the host in maintenance mode for you.




what are limitation of snapshot

Limitation of Snapshot



Snapshot can affect VM performance and do not support some disk type. Snapshots are useful as short term solutions for capturing point in time VM’s state’s and are not appropriate for long term VM backups.



1. VMware does not support snapshots of raw disks, RDM physical mode disks or OS that use an iSCSI initiate in the guest.
 2. VM’s with independent disk must be powered off before you take a snapshot. Snapshots of powered ON or suspended VM’s with independent disk are not supported.
3. Snapshots are not supported with PCI vSphere direct path I/O devices.
4. VMware does not support snapshots of VM’s configured for bus sharing. The alternative solution is to consider running backup software in your guest OS. If your VM currently has snapshots that prevent you from configuring bus sharing, delete or consolidate the snapshots.
5. Snapshots supports or provide point in time image of a disk that backup solutions can use but snapshot is not meant to be a method of backup and recovery. If the files containing a VM are lost, its snapshot files are also lost. Large numbers of snapshots are difficult to manage, consume large amount of disk space and are not protected in case of hardware failure.
6. It can negatively affect the performance of a VM. Performance degradation is based on how long a snapshot or snapshot tree is in place, the depth of a tree and how much the virtual machine and it’s guest OS have changed from the time you took the snapshot. It might have a delay in the amount of time It takes the VM to power ON.
 Note: Do not run production VM’s from snapshots on a permanent basis.



What is snapshot in VMware

This article will let you know about VMware snapshot

Virtual machine snapshots in VMware ESXi


If you are doing any activity in your production environment and something goes wrong then what? You will be in trouble and also having pressure from business to make that server up and running fine.
Here snapshot will help you. How?
First what is snapshot?


When you take a snapshot, you capture the state of a virtual machine settings and the virtual disk. If you are taking a memory Snapshot, you also capture the memory state of a VM (Virtual machine).


Note : They are not backup of virtual machines.


A snapshot consists of files that are stored on a supported storage device. A take snapshot operation creates: .vmdk-delta, .vmdk, .vmsd and .vmsn files.

1Vmname-number.vmdk and Vmname-number-delta.vmdkSnapshot files that represents the difference between the current state of the VD and state that existed at the time the previous snapshot was taken
2Vmname.vmsdDatabase of the VM’s snapshot information and the primary source of information for the snapshot manager
3Vmname.snapshot number.vmsnMemory state of the VM at the time you take the snapshot. This file is created each time you take a snapshot, regardless of the memory selection. This .vmsn is much smaller without memory than one with memory.


What is cloud computing? Types of cloud computing?

What is cloud computing? What types of cloud computing? Are we using cloud?


You can use application and hardware system without need to worry about how the application and system work, who is managing and where this is installed?

It doesn’t mean System is hosted on internet. This mean access shared application which is maintained by other. Example: Users log in into desktop or server and access systems in your data center. After that they store their files and documents. Here even they don’t know how the back end servers are maintained or managed by whom?

Cloud computing now approach one step further by allowing you to expand your business beyond traditional data center it allow you to access to hosted application and system and now a days it allows you to dedicated servers on demand when you need.


Cloud is divided into Three Major Service:

1. SaaS (Software as a Service)
2. PaaS (Platform as a Service)
3. IaaS (Infrastructure as a Service)
1. SaaS (Software as a Service)


This will facilitate you to access your shared applications and data over the network and internet.

This is used widely form of cloud computing today example: Gmail, Zimbra etc.

We just open the application and they work from anywhere. In this you are not able to change application functionality how this work but it will give you permission to change look example theme.


2. PaaS (Platform as a Service)

It provides a computing platform and a solution stack as a service.

Example:It allows your developers and programmers the ability to their content to pre-configured web servers, database and app servers without having to install or maintain any of the servers, hardware, operating systems and their application.

It gives you more control because here you have to upload content to app server or database server. But here you will not get full control for underlying server. This mean you are able to manage your application but still depending upon service provider.

This is stable environment because before doing anything like applying patches should be checked before implementing.


3. IaaS (Infrastructure as a Service)

It gives you access to dedicated virtual or physical machines that you manage and maintain.

 It gives you even more control than PaaS- SaaS. This provides you access of virtual machine and allow you to install services and software based on your requirement. It allows you to access underlying OS you can install patches as well.


Cloud Computing deployment Models:

1. Private 2. Public and 3. Hybrid





How to Configure an ESXi host as an NTP client

This Article describes How to Configure an ESXi host as an NTP client.


1. Select your ESXi host in the inventory and click the Configuration tab.
2. In the Software panel, click Time Configuration.
3. View the current settings, which show that the NTP client is stopped and that no NTP server is defined.


4. In the Time Configuration dialog box, perform the following actions.
    Option Action > Date and Time > Record the date and time > NTP Configuration
    Select the NTP Client Enabled check box and click Options.


5.  In General > Select the Start and stop with host check box.

6. In the NTP Daemon Options dialog box, click Add.
    Type the NTP server name or IP address: (Your NTP Server IP) > Click OK to close the Add NTP Server window. Select the Restart NTP service to     apply changes check box and click OK.
7. Click OK to exit the Time Configuration dialog box.
8. Verify that the Time Configuration pane lists the NTP server that you added and that the NTP Client is listed as Running.