VSPHERE 4.0 QUICK START GUIDE REVIEW
un•put•down•a•ble Pronunciation: (un"poot-dou’nu-bul), [key] —adj. Informal. Adjective meaning consistently and irresistibly interesting. Typically refers to a book that is so well written and entertaining as to be difficult to (literally) put down and pause away from. Normally a term used to describe novels, but the vSphere Quick Start Guide certainly fits the definition. Last month I was finishing three major projects and needed to write my VCDX application in one week, but somehow it kept ending up in my hands. So what’s so special about this book and how does it distinguish itself from the competition? The book central theme is providing tips and ‘how to’s’ and it does this rather well. The book handles the traditional subjects, such like vCenter, Host, Virtual Machines, Networking and Storage. Besides the concise, easy to follow and non-ambiguous way the tips are written, I really like the minimal use of screenshots. This allowed using the (limited) space to contain as much content as possible. Besides describing how to change settings via the Service Console CLI and the GUI, most tips also list PowerCLI and RemoteCLI example scripts. Incorporating PowerCLI scripts allows this book to be of value to the more experienced administrator who is using PowerCLI or RemoteCLI to manage its environment. The examples certainly increased my interest of picking up PowerCLI. But what really makes this book shine is the short in-depth text accompanying most of the tips and how to’s. The text contains valuable information on how certain mechanism works, what impact changing a setting can have and field experience of using certain settings. Added bonus is addressing the possibility of using third-party tools such as Dell expart, EMC powerpath VE, vwire and many others, confirming that this book is written by authors with true field experience. I really recommend this book to anyone who is using VMware ESX. It doesn’t matter if you are a novice administrator or a seasoned consulting architect, you WILL learn something new by reading this book. During the ESX 2.5 era, anyone who was serious about his job owned the Advanced Technical Design Guide, in the current vSphere era it’s clear that this book must be on your desk.
VMWARE UPDATES TIMEKEEPING BEST PRACTICES
A couple of weeks ago I discovered that VMware updated its timekeeping best practices for Linux virtual machines. December 7th VMware published a new best practice of timekeeping in Windows VMs. (KB1318) VMware now recommends to use either W32Time or NTP for all virtual machines. This a welcome statement from VMware ending the age old question while designing a Virtual Infrastructure; Do we use VMware tools time sync or do we use W32time? If we use VMware tools, how do we configure the Active Directory controller VMs? VMware Tools can still be used and still function well enough for most non time sensitive application. VMware tools time sync is excellent in accelerating and catching up time if the time that is visible to virtual machines (called apparent time) is going slowly, but W32time and NTP can do one thing that VMware tools time sync can’t, that’s slowing down time. Page 15 of the (older) white paper: Timekeeping in VMware Virtual Machines http://www.vmware.com/pdf/vmware_timekeeping.pdf explains the issue.
ESX 4I SUPPORT JUMBO FRAMES
Last week I blogged about jumbo frames being unsupported in ESX 4i. Yesterday Charu Chaubal, Sr. Technical Marketing Architect at VMware blogged the following; I am happy to say that this is merely an error in the documentation. In fact, ESXi 4.0 DOES support Jumbo Frames on VMkernel networking interfaces. The correction will hopefully appear in a new release of the documentation, but in the meantime, go ahead and configure Jumbo frames for your ESXi 4.0 hosts.
TIMESAVERS FOR VCDX APPLICATION
Last week VMware send out the invitations for the VCDX defend session at the Partner Exchange Las Vegas 2010. Like many others I’m trying to finish my application on time. So any help, shortcut and timesavers will help realize the goal. At this moment these tools and shortcuts save me lots of time: Puretext Steve miller created a simple but awesome tool. Puretext will strip any formatting while pasting text. This IS the lifesaver for me at the moment, because I’m copying text from older documents with different Fonttype and size. Run the small exe file and start loving the windows key + v command. http://www.stevemiller.net/puretext/ Visio shapes Besides using graphics from the official VMware Branding Team, I also use visio shapes from the Xtravirt Presentation Pack 2.1. (needs registration) http://viops.vmware.com/home/servlet/JiveServlet/download/1514-2-5957/VMware-Stencil1-vSphere.zip http://viops.vmware.com/home/servlet/JiveServlet/download/1514-2-5966/VMware-Stencil2-vSphere.ziph http://xtravirt.com/presentation-pack Visiocafe will offer some really sweet vendor shapes, this will make your presentation look even more impressive :) http://www.visiocafe.com/vsdfx.htm Visio shortcuts:
IMPACT OF MISMATCH GUEST OS TYPE
During Healthchecks I frequently encounter virtual machines configured with the incorrect Guest OS type specified. Incorrect configuration of Guest OS of the virtual machine can lead to; • Reduction of performance • Different default type for the SCSI device * • Different defaults of devices • Wrong VMware Tools presented to the Guest OS resulting in failure to install • Inability to select virtual hardware such as enhanced vmxnet, vmxnet3 or number of vCPUs. • Inability to activate features such as CPU and Memory Hot Add. • Inability to activate Fault Tolerance. • VM burning up 100% of CPU when idling (rare occasions) Buslogic SCSI Device * Due to mismatch of Guest OS Type, windows 2000 and Windows 2003 can be configured with a Buslogic SCSI device. Using the Buslogic virtual adapter with Windows 2000 and 2003 will limit the effective IO queue depth of one. This limits disk throughput severely and lead to serious performance degradation. For more information visit KB article [1614](http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1614&sliceId=1&docTypeID=DT_KB_1_1&dialogID=53698934&stateId=0 0 53706353) Virtual Machine Monitor and execution mode Selecting the wrong Guest OS type can be of influence of the selected execution mode. When a virtual machine is powering on, the VMM inspects the physical CPU’s features and the guest operating system type to determine the set of possible execution modes. This can have a slight impact on performance and in some extreme cases application crashes or BSODs. VMware published a Must-Read whitepaper about the VMM and execution modes http://www.vmware.com/files/pdf/software_hardware_tech_x86_virt.pdf How to solve the mismatch? vCenter only displays the configured Guest OS of the Virtual Machine, it will not check the installed operating system inside the virtual machine. Powercli offers the solution to this problem, today more and more people start to discover the beauty of Powercli and incorporate this in their day-to-day activities. So I’ve asked PowerCLI guru Alan Renouf if he could write a PowerCLI script which can detect the Guest OS mismatch.
IMPACT OF MEMORY RESERVATION
I have a customer who wants to set memory reservation on a large scale. Instead of using resource pools they were thinking of setting reservations on VM level to get a guaranteed performance level for every VM. Due to memory management on different levels, using such a setting will not get the expected results. Setting aside the question if it’s smart to use memory reservation on ALL VM’s, it raises the question what kind of impact setting memory reservation has on the virtual infrastructure, how ESX memory management handles memory reservation and even more important; how a proper memory reservation can be set. Key elements of the memory system Before looking at reservations, let’s take a look what elements are involved. There are three memory layers in the virtual infrastructure: • Guest OS virtual memory - Virtual Page Number (VPN) • Guest OS physical memory - Physical Page Number (PPN) • ESX machine memory - Machine Page Number (MPN) The OS inside the guest maps virtual memory ( VPN) to physical memory(PPN). The Virtual Machine Monitor (VMM) maps the PPN to machine memory (MPN). The focus of this article is on mapping physical page numbers (PPN) to Machine Page Number (MPN). Impact of memory management on the VM Memory reservations guarantee that physical memory pages are backed by machine memory pages all the time, whether the ESX server is under memory pressure or not. Opposite of memory reservations are limits. When a limit is configured, the memory between the limit and the configured memory will never be backed by machine memory; it could either be reclaimed by the balloon driver or swapped even if enough free memory is available in the ESX sever. Next to reservations and limits, shares play an important factor in memory management of the VM. Unlike memory reservation, shares are only of interest when contention occurs. The availability of memory between memory reservation and configured memory depends on the entitled shares compared to the total shares allocated to all the VMs on the ESX server. This means that the virtual machine with the most shares can have its memory backed by physical pages. For the sake of simplicity, the vast subject of resource allocation based on the proportional share system will not be addressed in this article. One might choose to set the memory reservation equal to the configured memory, this will guarantee the VM the best performance all of the time. But using this “policy” will have its impact on the environment. Admission Control Configuring memory reservation has impact on admission control . There are three levels of admission control; • Host • High Availability • Distributed Resource Scheduler Host level When a VM is powered on, admission control checks the amount of available unreserved CPU and memory resources. If ESX cannot guarantee the memory reservation and the memory overhead of the VM, the VM is not powered on. VM memory overhead is based on Guest OS, amount of CPUs and configured memory, for more information about memory overhead review the Resource management guide. HA and DRS Admission control also exist at HA and DRS level. HA admission control uses the configured memory reservation as a part of the calculation of the cluster slot size.The amount of slots available equals the amount of VM’s that can run inside the cluster. To find out more about slot sizes, read the HA deepdive article of Duncan Epping. DRS admission control ignores memory reservation, but uses the configured memory of the VM for its calculations. To learn more about DRS and its algorithms read the DRS deepdive article at yellow-bricks.com Virtual Machine Swapfile Configuring memory reservation will have impact on the size of the VM swapfile; the swapfile is (usually) stored in the home directory of the VM. The virtual machine swapfile is created when the VM starts. The size of the swapfile is calculated as follows:
NFS AND IP-HASH LOADBALANCING
My background is Fibre Channel and beginning 2009 I implemented a large iSCSI environment. The “other” storage protocol supported by VMware, NFS, is rather unknown to me. And to be honest I really tried to keep away from it as much as possible, thinking it was not a proper enterprise worthy solution. That changed this month as I was asked to perform a design review of an environment which relies completely of NFS storage. This customer decided to use IP-Hash as load-balancing policy for their NFS vSwitch, but what Impact does this have on the NFS environment?
UPGRADING TO SRM 4 AND SSL CERTIFICATES
Recently I started to work on a project implementing SRM 4. One of the project requirements is to use SSL certificates issued by a trusted CA. When upgrading to SRM 4, we ran into a small problem. Because of a change in the vCenter authentication protocol, a new certificate that complies with the new certificate content rules must be obtained. The requirements changed of the “Subject Alternative Name”, the SSL certificate issued for SRM 1 environments use the FQDN of the vCenter server host. In SRM 4 environments, the Subject Alternative Name field must contain the FQDN of the SRM server. This value will be different for each member of the SRM server pair. We installed the SRM server on a separate server, but If you have installed SRM on the vCenter server, then you do not need to acquire a new certificate.
LEFTHAND SAN – LESSONS LEARNED
Disclaimer: This article contains references to the words master and slave. I recognize these as exclusionary words. The words are used in this article for consistency because it’s currently the words that appear in the software, in the UI, and in the log files. When the software is updated to remove the words, this article will be updated to be in alignment. Please note that this article has been written in 2009. I do not know if Lefthand changed their solution. Please check with your HP representative for updates! I recently had the opportunity to deliver a virtual infrastructure that uses HP Lefthand SAN solution. Setting up a Lefthand SAN is not that difficult, but there are some factors to take into consideration when planning and designing a Lefthand SAN properly. These are my lessons learned.
TIMEKEEPING BEST PRACTICES FOR LINUX
VMware KB article 1006427 presents best practices for Linux timekeeping. These recommendations include specifics on the particular kernel command line options to use for the Linux operating system of interest. There is also a description of the recommended settings and usage for NTP time sync, configuration of VMware Tools time synchronization, and Virtual Hardware Clock configuration, to achieve best timekeeping results. What surprised me is the recommendation done by VMware; “Note: In all cases use NTP instead of VMware Tools periodic time synchronization” http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1006427