We are moving virtual machine from old storage to new datastore today, there are a lot of old datastores need to be removed after migration, for saftey consideration, I move all old datastore to a folder and then do decommission process.
There are more than 60 datastores, and vSphere client not allow move in one time. Here is a PowerCLI script can help move multiple datastores to a folder.
Note: Please make sure your folder name is uniquely.
When you create datastores.txt, please make sure first line is “Name”, one datastore name in each line.
A lot of storage support hardware acceleration, it is able to offload some storage operation from ESXi 5.x host to storage filer, the feature can significantly improve performance during cloning, vMotion, coping…etc.
Different storage device may support different features of hardware acceleration, block device have block zero, full copy, hardware assisted locking, thin provisioning, NAS device have extended stats, file cloning, large scale native SS, native SS to LC, space reserve.
You can find the detail information in this article.
For block storage, we initially create VMFS5 datastore by one LUN, more LUN (extent) maybe added to the datastore when free space is low. Please be sure that all extent of VMFS5 datastore should have same ATS feature, support or not. You may see a error message “Operation failed, unable to add extent to filesystem” when you add a non-ATS extent to ATS enabled VMFS5 datastore.
How to know if lun support ATS?
You can login ESXi 5.x host via SSH and use the command to see supported feature of a lun.
esxcli storage core device vaai status get -d=device id
What is ATS?
Atomic Test and Set (ATS) is new SCSI locking method, it’s try locking per disk sector instead of reserve entire lun. More detail information in this article.
Guest OS of virtual machine can synchronize time by several way, such as NTP, VMware Tools, Windows Time Service, CMOS…etc.
VMware Tools synchronize time with ESXi host when you enable periodic time synchronization. VMware Tools time synchronization function is disabled by default, but that’s doesn’t means time synch never happens between guest OS and host. It still happens after certain operations:
- When the VMware Tools daemon is started.
- When resuming a VM from suspended status.
- After reverting from a snapshot.
- After shrinking a disk.
It can causes some problem if guest OS have different time with host, it can lead to SAP application failed due to SAP database timestamp different with guest OS.
You can completely disable the time synchronization by following step:
- Power off the VM.
- Add following lines to .vmx file.
tools.syncTime = “FALSE”
time.synchronize.continue = “FALSE”
time.synchronize.restore = “FALSE”
time.synchronize.resume.disk = “FALSE”
time.synchronize.shrink = “FALSE”
time.synchronize.tools.startup = “FALSE”
- Save and close the file.
- Power on the VM.
You can also refer VMware official document.
Here is also a useful KB article for timekeeping best practices for Linux VM.
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