This post is all about the errors and warnings you get with VMotion. For the most part VMotion works without an issue out of the box – unless the pre-reqs have been met (heck, you could say that about any piece of software I guess…) Occasionally, a setting on a vSphere host or VM can cause either a warning or an error. For the most part these are well explained in the UI which you simply read, and then fix the offending setting. Where things can tricky is when VMotion is leverage for some other function such as DRS or maintanance mode. If there errors you can find the vSphere host stuck at 2% in maintanance mode which can never complete. Remember DRS if you have it enabled does have “Faults” option which will tell you why you have a problem, and handy link to the Troubleshooting Guide…
As ever with software most problems stem from poor or inconsistent administration. Once the basic requirements have been met there are number of situations that can trigger errors or warnings on during the “compatiability” check or cause VMotion to fail altogether. These warnings occur due to setting on the physical vSphere host or the properties of the VM, and are summarized below. Errors must be resolved for the feature to work, but warnings can be bypassed in the interface – and this quite an important distinction. Errors are show-stoppers for manual or automated VMotions, warnings are much less a serious concern.
Ideally, a manual VMotion should trigger no errors or warnings to give the VM Operator a seamless experience. In my experience the best approach is to permissions can be used to disable options and features for these vCenter users to stop them making configuration changes in the first place – and to always ask if these folks have been granted more rights than they really need… That said, I find in my own daily admin I’m often inconsistent – and in a hurry. I rush to make a configuration change, get distracted, and never go back to undo the piece of admin I will know will cause problems later. It’s called human error in the trade…
VMotion Errors
- Storage Errors
In a classic configuration VMotion requires that the VM files be accessible to both the source and destination vSphere hosts. If for example a VM is placed on a local VMFS volume, which is accessible just to the source vSphere host then an error message will appear. Most SysAdmins resolve this problem by using Storage VMotion or Cold Migrate to relocate the files. To prevent VM Operators from creating VMs on local storage there are couple of options – If the host boots via FC-SAN, iSCSI-SAN, USB/SD-CARD or PXE then there is no real requirement for a local VMFS volume. Alternatively, local storage can be grouped into datastore folders, and the permissions assigned to stop operators from accessing it.
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