Write Technology in Cache

In this post, I want to briefly describe three types of caches: write-through, write-back, and write-around. The cache is semiconductor memory where data is placed temporarily to reduce the time required to service I/O requests from the host. Write operations with cache provide performance advantages over writing directly to disks. A write operation with cache is implemented in three ways which have its advantages and disadvantages. Write-back cache: Data is placed in cache and an acknowledgment is sent to the host immediately. Later, data from several writes are committed to the disk. Write response times are much faster because the write operations…

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vCenter appliance boot to emergency mode due to a corrupted file system

After I had to restart vCenter for some reason, this server failed to boot properly and went into the Emergency Mode. The appliance fails to start and reports the following message: To find out the root cause of this error, open the vCenter Console and scroll up (Shift + Page Up) the screen to see the first error. As you can see, one of the partitions “/dev/core_vg/core” is corrupted and it’s filesystem needs to be checked. First, check that none of your filesystems are full, enter the root password and type shell to access the bash shell and then type “df…

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Get ESXi Hardware Information with Command

While resting at home, a friend contacted me and said he was looking for hardware information from his servers because he was going to increase the amount of RAM and upgrade the server’s memory to higher size and asked me to help him in order to find the memory information such as empty slot and part number. Their servers are HP and ESXi 6 is installed, and I asked him to check through the ILO, but unfortunately, ILO was not configured.So I had to look for a way to get the server information via ESXi, so I started searching for…

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The SSL certificate of STS service cannot be verified

After I replace my new VCSA certificate with embedded PSC, I see the disconnected status in the NSX Manager dashboard in the Lookup Service section. When I try to configure Lookup Service in the NSX Manager I got the following error and after googling I find this KB, as in this KB mentioned, I check the port again but everything seems to be ok. However, I thought it was a certificate problem because before replacing the certificate it worked correctly.  Until I came across this article, which helps me a lot and I summarize it here. Although this article is for…

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Replacing vCenter Server Certificates Rollback at 85%

Today I was replacing VMCA certificates by an ADCS (Active Directory Certificate Service) signed certificate, which everything went well except when I imported my certificate, the procedure stuck at 85 percent and rollbacked. and show you an error with this title. Status : 85% Completed [starting services…]Error while replacing Machine SSL Cert, please see /var/log/vmware/vmcad/certificate-manager.log for more information. When you go to read the “certificate-manager.log”, you see an entry like this: Error Failed to start vmon services.vmon-cli RC=1 After a lot of searching on the internet, I sum up with this good article which helps me to solve my problem. The procedure…

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Finding Latency Problem in ESXi

One of the common problems in software-defined datacenters is the latency of the virtual machine disk which will slow down the application and increase response time. The virtual machine owner or user declares that its system is slow and the question arises whether the slowdown is coming from a virtual infrastructure or storage device or operating system and how to troubleshoot it? In this section, we will discuss the storage parameters in VMware ESXi and show you how troubleshot disk latency in your environment. Lets SSH to ESXi host and leverage esxtop command to identify the problem. Esxtop allows monitoring…

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Upgrade VMFS 5 to VMFS 6

3 versions of the VMFS file system have been released by VMware for ESXi hosts which include VMFS3, VMFS5, and VMFS6. To fully understand the differences between these VMFS versions check this link.Today, after the successful installation of ESXi 6.7 on HP DL380 G9 in one organization, we have decided to update their datastores from version 5 to 6. So I read VMware docs for more information about the procedure of upgrading and got some valuable information which here is the summary: You can leverage the new VMFS 6 capabilities by creating a new VMFS 6 datastore and you cannot…

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Add VMkernel adapter to a number of ESXi hosts

Currently, I’m working with a customer who was wanting to add new VMkernel to their ESXi hosts and the number of ESXi hosts is about 50. Doing this task by vSphere Web Client was a bit time consuming and it is worth to write a script to this task automatically in a few seconds.While I was working on scripting I faced different problems and decided to share my experience with you!We are using the PowerCLI command to create the VMkernel Ports. If you have not Installed PowerCLI in PowerShell, See the following link. In order to add new VMkernel for…

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How To Install VMware PowerCLI via PowerShell

The installation is done completely through PowerShell itself using the PowerShell Gallery via PowerShellGet. To install the PowerCLI 11, you just need to open the PowerShell with administrative privilege and type the following command to run the installation. Install-Module -Name VMware.PowerCLI -RequiredVersion 11.1.0.11289667 -Scope AllUsers PowerCLI will automatically be installed for all users. If you want to limit the installation to a specific user, change the Scope parameter to “CurrentUser”. You will be asked to trust the PSGallery modules, as PowerCLI is one of them. If you are running a self-signed certificate for vCenter Server, you need to run the following…

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Horizon View 7 – Initial Horizon View Configuration

In this post, we are about configuring the Connection Server so that it can create pools of VDI desktops. We use the Horizon Administrator UI to perform these Connection Server configuration tasks. Before we create a desktop pool we must have the following parameters configured: Horizon 7 license vCenter Server user account – See Horizon View 7 – Prepare Active Directory View Composer Server user account– See Horizon View 7 – Prepare Active Directory View Composer Server user account – See Horizon View 7 – Prepare Active Directory Horizon 7 License In Horizon Administrator, navigate to View Configuration, and select Product Licensing…

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