Category: How To

Sometimes, you have to change permissions on all files within a directory or change permissions on all sub-directories in a directory. You know, we use some commands to change permission such as “chmod” or “setfacl” or other commands. But in this scenario, we want to changes all files permission in a directory and its sub-directories or change permission for all sub-directories. There is a regular command: chmod -R 755 /DirectoryPath Read and execute permissions will be granted by this command to all your directories and files but this is not working for our scenario. You can run the below command for give proper permissions to directory or sub-directories: find /path/to/base/dir -type d -exec chmod 755 {} + Or chmod 755 $(find /path/to/base/dir -type d) Or find /path/to/base/dir -type d -print0 | xargs -0 chmod 755 Also you can run same commands for files: find /path/to/base/dir -type f -exec chmod 644 {} + Or chmod 644 $(find /path/to/base/dir -type f) Or find /path/to/base/dir -type f -print0 | xargs -0 chmod 644 I hope, this post will help you to address your some permission issues.

Queues Queues are often misrepresented as the very “bane of our existence” and yet queues restore some order of semblance to our chaotic life. Queue depth is the number of I/O requests (SCSI commands) that can be queued at one time on a storage controller. Each I/O request from the host’s initiator HBA to the storage controller’s target adapter consumes a queue entry. Typically, a higher queue depth equates to better performance. Overview Of Queues There is three layer or queue stacks: Virtualization Stack At the Virtual Machine level, there are 2 queues PVSCSI Adapter queue Per VMDK queue You can find more information on this KB: 2053145 Server Stack At a physical Server level there are 2 queues  A HBA (Host Bus Adapter) queue per physical HBA A Device/LUN queue (a queue per LUN). Please consider that if you have some servers in a cluster, using same HBA on all servers is recommended. Also if you have different HBA adapters in hosts, you can change HBA queue depth. Read this KB: 1267 Read this KB: 2044993, if you have problem with your HBA driver on ESXi 5.5 and above. About any other storage adapter, you should read its vendor...

Problem Do you have Windows 7 as client OS in your VDI environment? If yes, so you should have WSUS server in your environment to download and push Microsoft updates for Windows. If you have WSUS, you need to keep started “Windows Update” service on your clients or even servers but sometimes, searching, downloading and installing updates has huge load on CPU and memory and impact on performance. These processes will impact performance when you don’t have many cores on virtual machines and it will occur on VDI clients more than servers because clients have few cores compare to servers. In my case, this issue impacted our “Call Center” users because they were working with VOIP application and CPU load has impact on voice in VDI environments. Solution Microsoft releasing updates and hot-fixes for Windows Update Client always. So keep update the client on your VDI clients. For example, Microsoft has released the below KB for resolving same issue on Windows 7 and Windows 2008 R2 recently. It’s recommended to applying the update as soon as possible to preventing any impact on client performance. KB3102810 Also you can read my previous post about same issue: Windows Update Scan – Memory...

Recently, Microsoft has announced PowerShell for Linux and OpenSource. We can use PowerShell abilities on other OSes such as enterprise Linux, Mac OSX and Ubuntu LTS (14.04 and 16.04). I want to explain installation process for CentOS 7 in this post. Installation PowerShell At first step, we should download the proper package for your OS, PowerShell package is available for the below OSes: Ubuntu 14.04 Ubuntu 16.04 CentOS 7 or RHEL 7 Mac OS Download it form the release page. After download, we can install RPM package on our Linux machine: rpm -i powershell-6.0.0_alpha.9-1.el7.centos.x86_64.rpm Done! Now, type “powershell” in terminal and you will be redirected to PowerShell console and you be able to run Powershell commands: Also there is no case sensitivity in this console! Unlike Linux commands! You can download other packages and install the packages on other supported Operating System. Please consider that the version is Alpha version and this is not final or stable version and there is some bugs and limitation. But I’m sure that new features will be added to the future versions.

Recently, we are working on Oracle virtualization (Oracle VM Server – Xen) solution on our lab and we have plan to deploy the solution on our Oracle (Sun) servers in production environment. At first step, we need to test the solution on our test servers and we don’t have enough resources to add additional servers to our farm just for the test. So we have to create some our server as virtual machines and test Oracle VM Server’s features such as DRS, DPM, Live Migration, Repository Migration and others. You know, you can deploy any hypervisor on your ESXi server by adding some parameters in the machine configuration file (VMX) but what is same solution for Oracle VM Server? Does it support nested virtualization? Oracle VM Server supports nested virtualization but I couldn’t find any solution on Oracle documentation center! But as you may know, Oracle uses Xen in its product as hypervisor, so I found my answer on this page: Nested Virtualization in Xen We should add some parameters to VM configuration file: hap=1 nestedhvm=1 There is some conditions: Xen 4.4 or later Intel CPU with EPT support You should read the wiki page for more information.