Category Archives: vSphere

Expand RDM in virtual compatibility mode

As opposed to the physical RDM mode with the virtual one after expanding the LUN on the storage array side and rescanning HBA vm still can’t see the increased capacity. The official VMware tutorial says to shutdown vm and re-add RDM. This isn’t acceptable.┬áThe hint to make it happen with no downtime is to vMotion vm after rescanning HBA on the destination host. That’s it!

Restarting managements agents

You know the situation when the host stops reporting its performance counters, do you? CPU and RAM load are showing nils.. A simple two-liner to fix the issue at your disposal:


Fast Suspend/Resume

Have you ever come across the term in subj? It’s time to reveal what it stands for.
First, three examples when this action can be performed.
To enable CBT for virtual machine in addition to make vm reconfiguration one need to perform so called stun/unstun cycle for vm. This could be power on/off, suspend/resume, create/remove snapshot, vm migration.
Another example is changing the build type for running vm (release/debug/stats). This can be done in vm advanced settings tab or via command line utils. In order to BuildType change is applied FSR is performed transparently by the 5.x hypervisor (for ESXi 4.x vm is actually suspended and then resumed).
And the most frequent one is hot-add hardware to vm.
In fact Fast Suspend/Resume equals to migration to the same host – that’s simple.

Below you can find an example of CBT enabling script (most of backup tools enable it automatically).

Veeam slow backup

One day I suddenly noticed that backup jobs could no longer fit the backup window. While investigating the issue I found tons of log records pointing that before processing every VM in the job Veeam tries to clean up all the snapshots created by its own for backup purposes. In some cases they were manually deleted or lost for some reason, but the records were still kept in the database.
So the root cause of slow backup is detected. To fix it first ensure that all backup jobs are stopped. If so, delete all snapshots with names containing ‘VEEAM’ and ‘Consolidate helper’ in vSphere inventory. Then go to Veeam database and clear the VmWareSnapshot table (DELETE FROM VmWareSnapshots). It’s recommended to stop VeeamBackup service before executing the query against DB.
That’s it. Restart your jobs and enjoy the rates you used to see!

vCenter Converter 5 low processing rate

If you experience too slow conversion speed while doing P2V migration or other conversion task and see no reason for this, the solution might be to disable SSL encryption for data transfers between agent and server. To accomplish this open the file ‘C:\ProgramData\VMware\VMware vCenter Converter Standalone\converter-worker.xml’, navigate to nfc section of xml and set false in useSSL tag. Restarting ‘Converter Worker’ service is required. Hope this’ll help!