I like to apply the following customizations to my vCenter Server (VCS) on IBM Cloud instance after deploying it:

SSH customizations

Out of the box, the vCenter customerroot user is not enabled to use the bash shell. After logging in as customerroot, you can self-enable shell access by running:

shell.set --enabled true

Note that in a future release, IBM expects to remove the need for the customerroot user and will provide the root credentials directly to you for newly deployed instances.

Additionally, I like to install my SSH key into vCenter so that I don’t need to provide a password to login. This involves two steps:

1. Copy my SSH public key to either /root/.ssh/authorized_keys or /home/customerroot/.ssh/authorized_keys. Note that if you create the folder you should set its permissions to 700, and if you create the file you should set its permissions to 600.
2. vCenter will only allow you to use key-based login if you set your login shell to bash:
   chsh -s /bin/bash

Note that your authorized key will persist across a major release upgrade of vCenter, but your choice of default shell will not. You will have to perform step 2 again after upgrading vCenter to the next major release.

Although SSH is initially disabled on the hosts, I also add my key to each host’s authorized keys list. For ESXi, the file you should edit is /etc/ssh/keys-<username>/authorized_keys as noted in KB 1002866.

Public connectivity

Some of your activities in vCenter benefit from public connectivity. For example, vCenter is able to refresh the vSAN hardware compatibility list proactively.

vCenter supports the use of proxy servers for some of its internet connectivity. Since I have access only to an http but not an https proxy, I configure this by manually editing /etc/sysconfig/proxy as follows:

PROXY_ENABLED="yes"
HTTP_PROXY="http://10.11.12.13:3128/"
HTTPS_PROXY="http://10.11.12.13:3128/"

Alternately, if your instance has public connectivity enabled, you can configure vCenter routes to use your services NSX edge to SNAT to the public network. This involves the following steps:

1. Login to NSX manager and select Security | Gateway Firewall, then manage the firewall for the T0 gateway with “service” in its name. Add a new policy for “vCenter internet” and add a rule to this policy with the same name and set to allow traffic. The source IP for this rule should be your vCenter appliance IP, and the destination and allowed services can be Any. Publish your changes. Note that these changes may be overwritten later by IBM Cloud automation in some cases if you deploy or remove add-on services like Zerto and Veeam.
2. Still in NSX manager, select Networking | NAT. Verify that there is already an SNAT configured for the T0 service gateway that allows all 10.0.0.0/8 traffic to SNAT to the public internet.
3. Identify the NSX edge’s private IP so that we can configure a route to it later. Still in NSX manager, navigate to Networking | Tier-0 Gateways, and expand the gateway with “service” in its name. Click the number next to “HA VIP configuration” and note the IP address associated with the private uplinks, for example, 10.20.21.22.
4. Login to the vCenter appliance shell (or run appliancesh from the bash prompt). Run the following command to identify the IBM Cloud private router IP address. It will be the Gateway address associated with the 0.0.0.0 destination, for example, 10.30.31.1:
   com.vmware.appliance.version1.networking.routes.list
5. Now we need to configure three static routes to direct all private network traffic to the private router, substituting the address you learned in step 4 above. IBM Cloud uses the following IP networks on its private network:
   com.vmware.appliance.version1.networking.routes.add --destination 10.0.0.0 --prefix 8 --gateway 10.30.31.1 --interface nic0
com.vmware.appliance.version1.networking.routes.add --destination 161.26.0.0 --prefix 16 --gateway 10.30.31.1 --interface nic0
com.vmware.appliance.version1.networking.routes.add --destination 166.8.0.0 --prefix 14 --gateway 10.30.31.1 --interface nic0
6. Finally we can reconfigure the default gateway. First display the nic0 configuration:
   com.vmware.appliance.version1.networking.ipv4.list
7. In this configuration we want to modify only the default gateway address. Keeping all the other details we learned from step 6, and substituting the edge private IP address we learned in step 3, run the following command:
   com.vmware.appliance.version1.networking.ipv4.set --interface nic0 --mode static --address 10.1.2.3 --prefix 26 --defaultGateway 10.20.21.22

Note: If you follow the approach of setting up SNAT and customizing routes, in my experience this can cause problems when you upgrade vCenter to the next major release. It appears that the static routes configured in step 5 do not persist across the upgrade, resulting in no traffic being routed to the private network. Before starting a major release upgrade, you should set the vCenter default route that you configured in step 7 back to the IBM Cloud private router. After the release upgrade, you need to reintroduce the three routes you added in step 5 above, as well as updating the default route you set in step 7 to point to the NSX edge.

vSAN configuration

I customize my vSAN configuration as follows:

1. In vCenter, navigate to the cluster’s Configuration | vSAN | Services and edit the Performance Service; set it to Enabled.
2. Navigate to the cluster’s Configuration | vSAN | Services and edit the Data Services; enable Data-In-Transit encryption.

Firmware updates

Your host may be provisioned with optional firmware updates pending, and additional firmware updates may be issued by IBM Cloud at any time thereafter. Available firmware updates will be displayed on the Firmware tab of your bare metal server resource in the IBM Cloud console. You can update firmware for a host with the following steps:

1. In vCenter, place the host in maintenance mode and wait for it to enter successfully.
2. In the IBM Cloud console, perform Actions | Power off and wait for the host to power off.
3. In the IBM Cloud console, perform Actions | Update firmware. This action may take several hours to complete.
4. In vCenter, remove the host from maintenance mode.

Occasionally I have found that either the firmware update fails, or it succeeds but the success is not reflected in the IBM Cloud console and an update still appears to be available. In cases like this you can resolve the issue by opening an IBM Cloud support ticket.

IPMI

At deploy time, your bare metal servers have IPMI interfaces enabled. Although these interfaces are on your dedicated private VLAN, it is still a best practice to disable them to reduce the internal management surface area. You can do this using the SoftLayer CLI and providing the bare metal server ID that is displayed in the server details page in the IBM Cloud console:

slcli hardware toggle-ipmi --disable 1234567
slcli hardware toggle-ipmi --disable 3456789
. . .

Here are some important resiliency considerations if you are using NFS datastores for your VMware vSphere cluster. You should be aware of these considerations so that you can evaluate the tradeoffs of your NFS version choice in planning your storage architecture.

NFSv3 considerations

For NFSv3 datastores, ESXi supports storage I/O control (SIOC), which allows you to enable congestion control for your NFS datastore. This helps ensure that your hosts do not overrun the storage array’s IOPS allocation for the datastore. Hosts that detect congestion will adaptively back off the operations they are driving. You should test your congestion thresholds to ensure that they are sufficient to detect and react to problems.

However, NFSv3 does not support multipathing. This is not just a limitation on possible throughput, but a limitation on resiliency. You cannot configure multiple IP addresses for your datastore, and even if your datastore is known by a hostname, ESXi does not allow you to leverage DNS based load balancing to redirect hosts to a new IP address in case of interface maintenance at your storage array; ESXi will not reattempt to resolve the hostname in case of connection failure. Thus, NFSv3 is subject to the possibility that you lose the connection to your datastore in case of interface maintenance on your storage array.

NFSv4.1 considerations

NFSv4.1 datastores have the opposite characteristics for the above issues:

NFSv4.1 supports multipathing, so you are able to configure multiple IP addresses for your datastore connection. This possibly allows you to obtain better network throughput, but more importantly it helps to ensure that your connection to the datastore is resilient in case one of those paths is lost.

However, at this time NFSv4.1 does not support SIOC congestion control. Therefore, if you are using NFSv4.1 you run the risk of triggering a disconnection from your datastore if your host—or especially if multiple hosts—exceeds your storage array’s IOPS allocation for the datastore.

With the new vSAN Express Storage Architecture (ESA), you may need to carefully plan your migration path from vSAN 7 to vSAN 8. At the moment, VMware only supports greenfield deployments of vSAN ESA. As a result, even if you have a vSAN cluster with NVMe storage, you will need to migrate your workloads to a new cluster to reach vSAN ESA. Furthermore, if you are moving from SSD to NVMe, you’ll need to ensure your order of operations is correct.

The following graph illustrates your possible migration and upgrade paths:

Your fastest path to ESA is to leave your existing cluster at the vSphere 7 level and create a vSphere 8 ESA cluster after upgrading to vCenter 8.

It’s important to consider both your vSphere and vSAN licensing during this process. For one, you will incur dual licensing for the duration of the migration. But you should also be aware that your vSAN license is tied to your vCenter version rather than your vSphere version. KB 80691 documents the fact that after upgrading to vCenter 8, your vSAN cluster will be operating under an evaluation license until you obtain vSAN 8 licenses. You should work with VMware to ensure both proper vSphere and vSAN licensing throughout this transition process.