Back To My Basics | NPIV


When we discussed about WWN in my Back To My Basics series, we talked about WWNN and WWPN. Normally for a dual port HBA card in a server, there will be two WWPN and one WWNN. This is pretty fine for a normal standalone server. But what if this server is used as a VMware Hypervisor, and one of the VM inside this hypervisor has a requirement to have a direct FC connection to SAN. In the current scenario, it is somewhat possible via RDMs or Raw Device Mapping. For mapping an RDM, a LUN is directly presented to the WWPNs of all ESXi hosts in the cluster and that LUN can be mapped as a RDM disk to the VM. But still the VM is not close enough to the storage and there exists an intermediate, the ESXi, as VM uses the WWPN of the host HBA of ESXi for connectivity. This gap can be bridged using NPIV.

NPIV stands for N_Port ID Virtualization. This is an ANSI T11 standard which enables the mapping of multiple virtual WWNs to a single physical HBA port (WWPN). Now the hypervisor is not limite…

Back To My Basics | WWN, WWNN and WWPN

I've been posting blogs on various features and troubleshooting tips over the past few years. But I think it is time to go back to my basics. Something which I feel as the building block of a good system admin. In this 'Back To My Basics' series, I'll be revisiting some of the system basics.

You may be an administrator in VMware, Windows, Linux or even network. Do you think that you always get to hear something only from your area of expertise ? definitely not...The basics should be strong enough for you to understand technologies in the course of design or engineering discussions.


We all know about MAC address, it doesn't need any special introduction. MAC is an unique identifier of a Network Adapter. Network is one of the communication channel of the server. For attaching storage, we may use the same network if the storage is iSCSI based. If the traffic uses FC, we may need something called as an HBA (Host Bus Adapter) card in our server. HBA card is similar t…

VMware and Windows Interview Questions: Part 9

How can I change the EVC mode of an existing cluster?You need to shutdown all running VMs in that cluster to change the EVC modeWhat if reconnecting the ESXi host back to an EVC cluster fails?Make a note of the VM foldersRemove the ESXi host from the inventoryAdd the ESXi host directly to the vCenter outside the EVC clusterNow move the server to the EVC clusterAdd the VMs back to the foldersWhat is PSC?PSC is Platform Service ControllerThis is an extended SSO model which was there in pre 6.0 versionsIt takes care of authentication,licensing,certificates etc..What are the two deployment models of PSC?Embedded & ExternalEmbedded if PSC is installed in vCenter boxExternal if PSC is installed outside vCenter in separate boxHow can I check if storage is VAAI capable?Check datastore and confirm if it supports Hardware AccelerationWhat is vmx~?In addition to the normal vmx file, from vSphere 6.0 onwards there is an additional file vmx~vmx~ first takes any configuration changes and then w…

VMware and Windows Interview Questions: Part 5

1.What’s the number of permitted unsuccessful logons for Administrator account? a.Unlimited - Only for Administrator, not for others in Administrators group 2.Difference between Everyone and Authenticated users? a.Authenticated Users - Include all Users and Computers whose identities have been authenticated. b.Everyone - For Windows 2003 and above, 'Everyone' includes all Authenticated Users including Guest accounts. Before Windows 2003, 'Everyone' includes all Authenticated Users , Guest accounts and Anonymous account. 3.How many passwords by default are remembered when you check “Enforce Password History Remembered”? a.24 4.What is an IP Helper address feature and why is it required in a DHCP environment ? a.IP helper-address helps to implement DHCP relay agent in Cisco routers b.This is configured at the network interface of the router containing the DHCP client c.The IP helper-address intercepts the DHCP discover message from the client and unicasts it to the DHCP server aft…

VMware and Windows Interview Questions: Part 6

1.Can we setup an AD site  without a DC ? a.Yes.. 2.What is DAS ? How is it connected to the server ? a.DAS is Direct Attached Storage. DAS is available with many vendors. When a server has exhausted all its storage resource, we can connect a DAS solution to it. DAS can be connected to a server using SAS cable. 3.How is an iscsi device connected to a server ? a.An iscsi device can be connected using the iqn number. 4.How can I add new HDD space to an existing drive ? a.Convert the drive from Basic to Dynamic 5.What happens when a standalone host is taken into maintenance mode ? a.The activity will wait until all VMs are shutdown. 6.What if all GC in the environment are down ? a.GC is required for multi domain forests - In a single domain infrastructure, the DCs will not contact the GC for authenticating. But in multi domain infrastructure, GC is required for authentication. b.Universal Group Membership evaluation - Universal Group Membership which exists in a multi domain forests works only with …

VMware and Windows Interview Questions: Part 8

1.Can you map a single physical NIC to multiple virtual switches ? oNo 2.Can you map a single virtual switch to multiple physical NICs? oYes. This method is called NIC teaming. 3.In vSphere 5.5, VMKernel portgroup can be used for: ovMotion oFault Tolerance Logging oManagement traffic 4.Major difference between ESXi 5.1 and ESXi 5.5 (above) free versions oTill ESXi 5.1 free version there was a limit to the maximum physical memory to 32 GB. But from 5.5 onwards this limit has been lifted. 5.What is IPAM server in Windows server 2012? o IPAM is IP Address Management server in Windows Server 2012. It enables central management of both DHCP and DNS servers. It can also be used to discover, monitor, and audit DHCP and DNS servers. 6.How to promote a server to domain controller in Windows server 2012? oDCPROMO was the conventional tool used to promote a normal server to DC. This is now deprecated in Server 2012.  oIn Server 2012, you can convert a server into DC using the server manager console. Under Ser…

VMware and Windows Interview Questions: Part 7

1.Which networking features are recommended while using iSCSI traffic oiSCSI port binding oJumbo Frames 2.Ports used by vCenter o80,443,902 3.What is 'No Access' role oUsers assigned with the 'No Access' role for an object, cannot view or change the object in any way 4.When is a swap file created oWhen the guest OS is first installed in the VM 5.The active directory group, where the members will be ESXi administrators by default. oESX Admins 6.Which is the command used in ESXi to manage and retrieve information from virtual machines ? ovmware-cmd 7.Which is the command used in ESXi to view live performance data? oesxtop 8.Command line tool used in ESXi to manage virtual disk files? ovmkfstools 9.Port used for vMotion o