DELL MXL VLT | Server administrator version

This blog will be taking server administrators through the VLT dilemma. The blog will not be discussing any networking concepts in detail as I'm not the right one to do so. :) ... But I can help you to understand the Dell MXL VLT concept. What is VLT ?  VLT  ( Virtual Link Trunking)  is a logical domain which consists of multiple MXL switches. VLTi is the physical interconnect which connects the peer switches. In VLT, each peer switches will have its own management, data and control planes. All required protocols and configurations should be configured separately in each switch. The peer switches will exchange L2 related tables with each other. Uplinks from the switches can be bundled to an LACP. The ability to create LACP between the switches would eliminate the need of STP thereby increasing the link bandwidth. The only supported STP protocol is RSTP and is only used to avoid looping in case of incorrect cabling. How is it different to stacking ? In stacki

Back To My Basics | NPIV

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

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. WWN 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 c

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 mode What if reconnecting the ESXi host back to an EVC cluster fails? Make a note of the VM folders Remove the ESXi host from the inventory Add the ESXi host directly to the vCenter outside the EVC cluster Now move the server to the EVC cluster Add the VMs back to the folders What is PSC? PSC is Platform Service Controller This is an extended SSO model which was there in pre 6.0 versions It takes care of authentication,licensing,certificates etc.. What are the two deployment models of PSC? Embedded & External Embedded if PSC is installed in vCenter box External if PSC is installed outside vCenter in separate box How can I check if storage is VAAI capable? Check datastore and confirm if it supports Hardware Acceleration What is vmx~? In addition to the normal vmx file, from vSphere 6.0 onwards there is an additional file vmx~

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

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.     

VMware and Windows Interview Questions: Part 8

1.      Can you map a single physical NIC to multiple virtual switches ? o     No 2.      Can you map a single virtual switch to multiple physical NICs? o     Yes. This method is called NIC teaming. 3.      In vSphere 5.5, VMKernel portgroup can be used for: o     vMotion o     Fault Tolerance Logging o     Management traffic 4.      Major difference between ESXi 5.1 and ESXi 5.5 (above) free versions o     Till 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? o     DCPROMO was the conventional tool used to promote a normal server to DC. This is now d