Author: tmahanta

VSAN calculator

The best sizing tool for VSAN: Quote from the site: The purpose of this tool is to help determine the hardware specifications for hosts in a Virtual SAN cluster required to run a set of virtual machines defined by a set of input characteristics. These important assumptions should be understood before using this tool: All hosts in the cluster are assumed to have an identical hardware profile, i.e. numbers of hard drives and flash devices, amount of physical RAM, and number of CPU cores All virtual machines are assumed to be identical in storage characteristics, i.e. number of VMDKs, size of VMDKs (assumed identical for all disks), number of snapshots, and virtual memory size All virtual machines are assumed to have the same Virtual SAN policy, i.e. number of failures to tolerate and number of disk stripes per object The tool is designed so that you can easily vary inputs to see the impact on the sizing output, thus allowing you to iterate manually for more sophisticated analyses. So now the question is how does it work??? Calculation of IOPS is a VSAN cluster is one of the most asked questions.O n the calculator, You can input how many VMs in the cluster, average VMs/Host, and some parameters for per-VM profiling. Then, it can tell you how many IOPS your cluster needs. For Server Virtualization: Total IOPS Required...

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What is Rebalance of Objects in VSAN and how does it work ?

Why do we need rebalance in VSAN cluster? When any capacity device in your cluster reaches 80 percent utilization, Virtual SAN automatically rebalances the cluster, until the utilization of all capacity devices is below the threshold. Cluster rebalancing evenly distributes resources across the cluster to maintain consistent performance and availability. Other operations can initiate cluster rebalancing: If Virtual SAN detects hardware failures on the cluster If Virtual SAN hosts are placed in maintenance mode with the Full data migration option If Virtual SAN hosts are placed in maintenance mode with Ensure accessibility when objects assigned FTT=0 reside on the host. Note: To provide...

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What is Resync of Objects in VSAN?

You can monitor the status of virtual machine objects that are being resynchronized in the Virtual SAN cluster. The following events trigger resynchronization in the cluster: Editing a virtual machine (VM) storage policy. When you change VM storage policy settings, Virtual SAN might initiate object recreation and subsequent resynchronization of the objects. Certain policy changes might cause Virtual SAN to create another version of an object and synchronize it with the previous version. When the synchronization is complete, the original object is discarded. Virtual SAN ensures that VMs continue to run and are not interrupted by this process. This...

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Best practices to upgrade VSAN

Before you attempt to upgrade vSAN, verify that your environment meets the vSphere hardware and software requirements. 1: Verify that vSAN 6.6 supports the software and hardware components, drivers, firmware, and storage I/O controllers that you plan on using. Supported items are listed on the VMware Compatibility Guide website at 2: Verify that you have enough space available to complete the software version upgrade. The amount of disk storage needed for the vCenter Server installation depends on your vCenter Server configuration. 3: Verify that you have enough capacity available to upgrade the disk format. If free space equal to the consumed capacity of the largest disk...

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Remove Disk Partition on VSAN

If you have added a device that contains residual data or partition information, you must remove all preexisting partition information from the device before you can claim it for vSAN use. VMware recommends adding clean devices to disk groups. When you remove partition information from a device, vSAN deletes the primary partition that includes disk format information and logical partitions from the device. Prerequisites: +++++++++++ Verify that the device is not in use by ESXi as boot disk, VMFS datastore, or vSAN. Procedure: ++++++++ Navigate to the vSAN cluster in the vSphere Web Client. Click the Configure tab. Under vSAN, click Disk Management. Select a host to view the list of available devices. From the Show drop-down menu at the bottom of the page, select Ineligible. Select a device from the list, and click the Erase partitions on the selected disks icon Click OK to confirm. If vCenter Server is inAccessible from vSphere Web Client below are the steps to manually remove and recreate a vSAN disk group using the ESX Command Line Interface (esxcli). To remove and recreate a disk group using esxcli commands: Note: These steps can be data destructive if not followed carefully. Log in to the ESXi host that owns the disk group as the root user using SSH. Run this one of these commands to put the host in Maintenance mode. There are 3 options: Note: VMware recommends using the ensureObjectAccessibility option. Failure to use this ensureObjectAccessibility mode or evacuateAllData mode may result in data loss. Recommended: Ensure accessibility of data: esxcli...

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