Yellow Bricks

by Duncan Epping

5.1

Manual vMotion and using DRS to select a host results in no migration?

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I had a question from a customer last week. He was doing a manual migration on a cluster which had DRS enabled. He was using the vSphere Web Client and was wondering if he should tick the “Allow host selection within this cluster” tickbox or not, as shown in the screen shot below. The customer decided not to tick the “host selection” tickbox and decided that DRS would pick the right destination for the virtual machine. After he clicked “Finish” he noticed that the “relocation” literally finished in seconds and he wondered if anything happened at all… When he looked at the virtual machine he noticed it was still located on the same host, how can that be?

Well the answer is fairly straight forward, in this case the DRS cluster was balanced and that is the typical situation for most clusters out there I would say. When initiating the vMotion workflow the Cluster was selected as a destination so DRS had to figure out what the best destination would be. Considering the cluster was in balance, there would be absolutely no point in moving this virtual machine so what did DRS decide? Indeed, destination = source.

If you are going through this workflow using the Web Client, make sure to tick “Allow host selection within this cluster” and select a destination other than your source… otherwise the effort was pointless.

Manual vMotion

Pinging from different VMkernel NICs using esxcli?

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Today I had a network issue in my lab, I still don’t have a clue what the issue was but I did discover something useful. I had 3 different VMkernel’s setup and I wanted to make sure each of the three had network connection to a specific destination address. After going through the esxcli command I bumped in to the following command which I found very helpful:

esxcli network diag ping -I vmk0 -H 10.27.51.132

In this case I use VMkernel Interface “vmk0” to ping to the address “10.27.51.132”. If I want to use a different VMkernel Interface I just specify it, so swap “vmk0” with “vmk1” for instance. Useful right?!

Replaced certificates and get vSphere HA Agent unreachable?

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Replaced certificates and get vSphere HA Agent unreachable? I have heard this multiple times in the last couple of weeks. I started looking in to it and it seems that in many of these scenarios the common issue was the thumbprints. The log files typically give a lot of hints that look like this:

[29904B90 verbose 'Cluster' opID=SWI-d0de06e1] [ClusterManagerImpl::IsBadIP] <ip of the ha master> is bad ip

Also note that the UI will state “vSphere HA agent unreachable” in many of these cases. Yes I know, these error messages can be improved for sure.

You can simply solve this by disconnecting and reconnecting the hosts. Yes it really is as simple as that, and you can do this without any downtime. No need to move the VMs off even, just right click the host and disconnect it. Then when the disconnect task is finished reconnect it.

 

** Disclaimer: This article contains references to the words master and/or slave. I recognize these as exclusionary words. The words are used in this article for consistency because it’s currently the words that appear in the software, in the UI, and in the log files. When the software is updated to remove the words, this article will be updated to be in alignment. **

Number of vSphere HA heartbeat datastores less than 2 error, while having more?

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Last week on twitter someone mentioned he received the error that he had less than two vSphere HA heartbeat datastores configured. I wrote an article about this error a while back so I asked him if he had two or more. This was the case, so next thing to do was to “reconfigure for HA” to clear the message hopefully.

The number of vSphere HA heartbeat datastores for this host is 1 which is less than required 2

Unfortunately after reconfiguring for HA the error was still there, next suggestion was looking at the “heartbeat datastore” section in HA. For whatever reason HA was configured to “Select only from my preferred datastores” and no datastores were selected just like in the screenshot below. HA does not override this so when configured like this NO heartbeat datastores are used, resulting in this error within vCenter. Luckily the fix is easy, just set it to “Select any of the cluster datastores”.

the number of heartbeat datastores for host is 1
the number of heartbeat datastores for host is 1

vSphere 5.1 Storage DRS Interoperability

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A while back I did this article on Storage DRS Interoperability. I had questions last week about this so I figured I would write a new article which reflects the current state (vSphere 5.1). I also included some details that are part of the interoperability white paper Frank and I did so that we have a fairly complete picture. This white paper is on 5.0, it will probably be updated at some point in the future.

The first column describes the feature or functionality, the second column the recommended or supported automation mode and the third and fourth column show which type of balancing is supported.

Capability Automation Mode Space Balancing I/O Metric Balancing
Array-based Snapshots Manual Yes Yes
Array-based Deduplication Manual Yes Yes
Array-based Thin provisioning Manual Yes Yes
Array-based Auto-Tiering Manual Yes No
Array-based Replication Manual Yes Yes
vSphere Raw Device Mappings Fully Automated Yes Yes
vSphere Replication Fully Automated Yes Yes
vSphere Snapshots Fully Automated Yes Yes
vSphere Thin provisioned disks Fully Automated Yes Yes
vSphere Linked Clones Fully Automated (*) Yes Yes
vSphere Storage Metro Clustering Manual Yes Yes
vSphere Site Recovery Manager Not supported n/a n/a
VMware vCloud Director Fully Automated (*) Yes Yes
VMware View (Linked Clones) Not Supported n/a n/a
VMware View (Full Clones) Fully Automated Yes Yes

(*) = Change from 5.0