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Quick Tip - OVFTool 4.3 now supports vCPU & memory customization during deployment

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In addition to adding vSphere 6.7 support and a few security enhancements (more details in the release notes), the latest OVFTool 4.3 release has also been enhanced to support customizing either vCPU and/or Memory from the default configurations when deploying an OVF/OVA.

Historically, it was only possible to modify these values if you were deploying to a vCloud Director endpoint using either --numberOfCpus or --memorySize. When deploying to a vSphere endpoint, these settings were not applicable and users would need to perform an additional operation calling into the vSphere API using whatever automation tool of choice to reconfigure the VM after deployment. It was not the end of the world but also not ideal if you simply wanted to make a minor modification to the default OVF/OVA you were deploying. I definitely ran into this a few times where having this functionality would have been very useful and I know number of customers have also shared simliar feedback in the past.

I had asked whether it was possible to support this use case and it looks like we already had an internal feature request added to the OVFTool backlog and with some additional customer feedback, we were also able to get this enhancement added to the latest release.

The existing --numberOfCpus and --memorySize accepts a VM Identifier (usually the name) followed by the value, for example

--numberOfCpus:Foo=4

The VM Identifier is to help with vApp deployments where you may have an OVF/OVA which is composed of multiple VMs of which you would like to customize each VM with different values. To ensure we do not break backwards compatibility, this pattern has also been extended when deploying to a vSphere endpoint. Having said that, most customers that I have talked to who use OVFTool generally deploy an OVF/OVA that is comprised of a single VM. In this case, rather than specifying the name of the VM again which is derived from --name property, you can simply use the wildcard asterisk (*) to simply apply it to all VMs within the OVF/OVA.

Here is an example of deploying a PhotonOS OVA which is configured with a default of 1 vCPU and 2GB memory and as part of our deployment using OVFTool, we will increase both vCPU to 2 and memory to 4GB:

ovftool --acceptAllEulas --name=Foo --numberOfCpus:'*'=2 --memorySize:'*'=4096 photon-custom-hw11-2.0-304b817.ova 'vi://*protected email*@192.168.30.200/VSAN-Datacenter/host/VSAN-Cluster'

How to simulate Persistent Memory (PMem) in vSphere 6.7 for educational purposes? 

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A really cool new capability that was introduced in vSphere 6.7 is the support for the extremely fast memory technology known as non-volatile memory (NVM), also known as persistent memory (PMem). Customers can now benefit from the high data transfer rate of volatile memory with the persistence and resiliency of traditional storage. As of this blog post, both Dell and HP have Persistent Memory support and you can see the list of supported devices and systems here and here.


PMem can be consumed in one of two methods:

  • Virtual PMem (vPMem) - In this mode, the GuestOS is actually PMem-aware and can consume the physical PMem device on the ESXi host as standard, byte-addressable memory. In addition to using an OS that supports PMem, you will also need to ensure that the VM is running the latest Virtual Hardware 14
  • Virtual PMem Disks (vPMemDisk) - In this mode, the GuestOS is NOT PMem-aware and does not have access to the physical PMem device. Instead, a new virtual PMem hard disk can be created and attached to a VM. To ensure the PMem hard disk is placed on the PMem Datastore as part of this workflow, a new PMem VM Storage Policy will be applied automatically. There are no additional GuestOS or VM Virtual Hardware requirement for this scenario, this is great for legacy OS that are not PMem-aware

Customers who may want to familiarize themselves with these new PMem workflows, especially for Automation or educational purposes, could definitely benefit from the ability to simulate PMem in their vSphere environment prior to obtaining a physical PMem device. Fortunately, this is something you can actually do if you have some additional spare memory from your physical ESXi host.

Disclaimer: This is not officially supported by VMware. Unlike a real physical PMem device where your data will be persisted upon a reboot, the simulated method will NOT persist your data. Please use this at your own risk and do not place important or critical VMs using this method.

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Quick Tip - What hashing algorithm is supported for ESXi Kickstart password?

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I had a question the other day asking whether the encrypted password which can be specified within an ESXi Kickstart file (denoted by the --isencrypted flag) can use a different hashing algorithm other than MD5? The answer is absolutely yes. In fact, MD5 as a default hashing algorithm has NOT been used for a number of releases, probably dating back to classic ESX (you know, the version that had the Service Console).

For all recent releases of ESXi including 5.5 to 6.7, the default hashing algorithm has been SHA512 for quite some time now. Below are two ways in which you can check which default hashing algorithm is currently being used:

Option 1 - SSH to ESXi host and take a look at /etc/pam.d/passwd


Option 2 - SSH to ESXi host and take a look at /etc/shadow and look at the field prior to the salt.

As a reference:

  • $1$ - MD5
  • $5$ - SHA256
  • $6$ - SHA512