Virtualization 4 of 4 – Networking

Virtual LAN (VLAN) Although VLAN emerged before virtualization and is not part of virtualization topic. I’d just like to start from here as a refresher. Suppose we have computers from finance department and computers from sales department all connected to a single layer-2 switch. There are at least three problems: 1) too many devices on … Read moreVirtualization 4 of 4 – Networking

Virtualization 2 of 4 – Graphics Computing

We covered hypervisor in previous post. In this article we focus on the virtualization of graphics computing resource. GPU vs CPU GPU is a specialized type of microprocessor primarily designed for quick image rendering. GPU appeared as a response to graphically intense applications that put a burden on the CPU and degrated computer performance. They … Read moreVirtualization 2 of 4 – Graphics Computing

Virtualization 1 of 4 – Hypervisor

In broad terms, virtualization of computing resource is about isolation of resources, at different levels. There are five levels of virtualization: Application level, such as JVM, .NET CLR Library (user-level API) level Operating system level, such as LXC, Docker, OpenVZ Hardware abstraction layer (HAL) level, such as VMware, Xen, etc Instruction set architecture (ISA) level … Read moreVirtualization 1 of 4 – Hypervisor

Performance Analysis

Overview In 2015, Brendan Gregg posted two great articles on Netflix blog: Linux Performance Analysis in 60 seconds, and Linux Perfomrance Tools. They have great value when I was in a urgency to spot performance issues. The articles cover the essential tools for performance troubleshooting, including: Check out load averages: w or uptime Print kernel … Read morePerformance Analysis

Setup WSL2 on Windows 10

This is not for Linux snobs, but rather for those who are stuck with a Windows work laptop, have to deal with Linux on a daily basis, and are not a fan of PuTTY. This posting provides the steps to setup Windows 10 so you get a work environment closer to a Linux one. The … Read moreSetup WSL2 on Windows 10

Balloons steal memory from virtual machines

I came across an ElasticSearch server (ESXi guest with 32GB physical memory) where the main process keeps dying of OOM. Even worse, after the OOM event, the free memory left is about 10G and Elastic Search cannot start because its JVM is set with -Xms16g in /etc/elasticsearch/jvm.options. So I need to address the OutOfMemory error. … Read moreBalloons steal memory from virtual machines

Storage Nitty-Gritty 3 of 5 – NAS and Object Storage

NAS (network attached storage) NAS server is dedicated to file-serving. NAS device runs its own specialized operating system that is optimized for file I/O, integrated hardware and software component that meets specific file-service needs, and performs file I/O better than a general-purpose server. NAS device can serve more clients than general-purpose servers and provide the … Read moreStorage Nitty-Gritty 3 of 5 – NAS and Object Storage

Storage Nitty-Gritty 2 of 5 – SAN

In direct attached storage (DAS), storage is server centric and the host owns the storage. The storage is fully dedicated to the server that owns it. Storage has evolved into information centric model. In this model, when a new server is deployed in the environment, storage is assigned from the same shared storage pool to … Read moreStorage Nitty-Gritty 2 of 5 – SAN

Overview of vSphere

This post is a summary of VMware’s white paper Introduction to VMware vSphere. ESXi is the hypervisor (virtualization layer) on bare metal servers that abstracts processor, memory, storage and networking resources into multiple virtual machines. It was previously known as ESX and VMware discontinued ESX at version 4.1 so only ESXi is provided at and … Read moreOverview of vSphere