Tech-Gen

Difference between esxtop and resxtop http://www.yellow-bricks.com/esxtop/ http://www.vreference.com/public/vReference-esxtop1.2.pdf http://kb.vmware.com/kb/1008205 http://www.vmwarearena.com/2012/08/esxtop-replay-mode.html 5 of the best posts for analysing results and statistics http://www.yellow-bricks.com/esxtop/ http://communities.vmware.com/docs/DOC-9279 http://www.vmware.com/pdf/esx2_using_esxtop.pdf http://simongreaves.co.uk/blog/esxtop-guide http://communities.vmware.com/docs/DOC-5240 Analysing CPU/RAM/Network/Performance http://communities.vmware.com/docs/DOC-3930 esxtop and resxtop are both performance monitoring tools for VMware environments, but their primary difference lies in how they are accessed. esxtop is run directly on the ESXi host's command line, while resxtop is a remote version, typically used through the vSphere Management Assistant (vMA) or vCLI, allowing monitoring from a remote system.  Detailed Explanation: esxtop: Runs directly on the ESXi host's c...

  vSphere Virtual disk types When you create a virtual machine in VMware vSphere, vSphere creates a new virtual hard drive for that virtual machine. The virtual hard drive is contained in a virtual machine disk (VMDK). The disk format you choose for the new virtual hard drive can have a significant impact on performance. You can choose one of the following formats when creating a virtual hard drive: Thin-provisioned Thin-provisioned lazy-zeroed Thin-provisioned eager-zeroed Thin-provisioned Advantages: Fastest to provision Allows disk space to be over-committed to VMs Disadvantages: Slowest performance due to metadata allocation overhead and additional overhead during initial write operations Over commitment of storage can lead to application disruption or downtime if resources are actually used Does not support clustering features When vSphere creates a thin-provisioned disk, it only writes a small amount of metadata to the datastore. It does not allocate or zero out any disk spac...

  Virtual Disk Types The following disk types are defined in the virtual disk library: ■ VIXDISKLIB_DISK_MONOLITHIC_SPARSE  – Growable virtual disk contained in a single virtual disk file. This is the default type for hosted disk, and the only setting in the  Virtual Disk API Sample Code  sample program. ■ VIXDISKLIB_DISK_MONOLITHIC_FLAT  – Preallocated virtual disk contained in a single virtual disk file. This takes time to create and occupies a lot of space, but might perform better than sparse. ■ VIXDISKLIB_DISK_SPLIT_SPARSE  – Growable virtual disk split into 2GB extents ( s  sequence). These files can to 2GB, then continue growing in a new extent. This type works on older file systems. ■ VIXDISKLIB_DISK_SPLIT_FLAT  – Preallocated virtual disk split into 2GB extents ( f  sequence). These files start at 2GB, so they take a while to create, but available space can grow in 2GB increments. ■ VIXDISKLIB_DISK_VMFS_FLAT  – Preallocated virt...

 VCF 9 Launched!  Quick Takeaways. hashtag#4CuttheClutter I am going to keep it simple. Compute, Storage, Network, VCF Operations, VCF Automation.  (1/4) COMPUTE 1. NSX VPCs in vSphere UI - NSX VPCs are now natively integrated to vCenter. Admins can now create and manage NSX VPCs and networks directly in vSphere UI/API/CLI. Removes need to switch between NSX and vSphere consoles. Even the network topology is visible through vCenter. [Refresher: VPC's are self contained and cant communicate with each other. Provides simple networking consumption for users at the same time adapted to large multi-tenant environments. From going forward, VPCs will be the core building blocks for VMware's 'Public Cloud Experience in your Private Cloud'. ]  2. NVMe Memory Tiering - Now you can utilise NVMe disks for memory. Both DDR and NVMe will be taken and will be presented as one to workloads. From VCF 9, NVMe used as a secondary memory tier on ESXi hosts. Increases memory pool, offloa...

 In vSphere, Permanent Device Loss (PDL) and All Paths Down (APD) are two distinct storage connectivity issues. PDL indicates a permanent and unrecoverable loss of a storage device, while APD signifies a temporary loss of access, where the system expects the device to potentially return. VMware vSphere, including VMware Cloud Foundation (VCF), provides mechanisms to handle both PDL and APD to ensure virtual machine availability.  Here's a more detailed explanation: Permanent Device Loss (PDL): Definition: PDL occurs when a storage device is permanently lost, meaning it's unlikely to be recovered. This can be due to hardware failure, a device being removed without proper procedures, or other unrecoverable errors.  vSphere Handling: vSphere interprets certain SCSI sense codes from the storage array as indicators of PDL. Once a PDL is detected, the ESXi host stops retrying I/O to the affected device and the affected VMs are failed over if VM Component Protection (VMCP) is en...

TPS (Transparent Page Sharing) and UNMAP TPS (Transparent Page Sharing) and UNMAP are distinct VMware vSphere features that address different aspects of resource management. TPS focuses on memory optimization by deduplicating identical memory pages across virtual machines, while UNMAP, a SCSI command, enables thin-provisioned storage arrays to reclaim unused space by identifying and discarding deleted blocks.  TPS (Transparent Page Sharing):  Function: TPS identifies and consolidates identical memory pages used by multiple VMs, reducing overall memory consumption.  Mechanism: It works by comparing the content of memory pages and storing only one copy if they are identical, effectively deduplicating memory.  Intra-VM vs. Inter-VM: TPS can operate within a single VM (intra-VM) or across multiple VMs (inter-VM).  Security Considerations: While TPS can enhance memory efficiency, it also presents a potential security risk as it can be exploited to access data on othe...

  Unlocking the Future of Private Cloud with VMware Cloud Foundation 9.0   The private cloud journey is evolving fast—and VMware Cloud Foundation (VCF) 9.0 brings a major leap forward. Having worked with customers across industries, I’ve seen firsthand the challenges of scaling, automating, and securing private infrastructure. VCF 9.0 addresses those challenges head-on. Let’s break down the innovations in this release and how they empower organizations to build a cloud-smart foundation for the future   Simplified Deployment and Day-0 Experience One of the standout improvements is the new streamlined installer. Day-0 operations—once complex and time-consuming—are now wizard-driven and policy-based. What used to take weeks can now be done in a matter of hours. This is a game-changer for IT teams looking to deploy new environments quickly and efficiently. For customers starting fresh or expanding their environments, the simplified workload domain creation is intuitive, reduc...

  🎭 Mock Interview Scenario (VMware L1) Interviewer: Hi, thanks for joining. Let’s begin with a few basics. ⸻ Q1: Can you explain what VMware ESXi is? You: Sure! VMware ESXi is a Type 1 hypervisor that installs directly onto physical servers. It allows us to create and run multiple virtual machines on a single physical host without needing a traditional operating system. ⸻ Q2: What is the role of vCenter Server? You: vCenter Server is used to centrally manage multiple ESXi hosts and their virtual machines. It enables features like vMotion, High Availability (HA), and Distributed Resource Scheduler (DRS). ⸻ Q3: What would you check if a virtual machine doesn’t power on? You: I would check if the host has enough available CPU and memory, make sure there is enough space in the datastore, and review the VM’s log files. I would also check licensing and permissions. If needed, I would restart management agents on the ESXi host. ⸻ Q4: What is the difference between thin and thick provisi...