If you are connected to a Cisco switch, remove security port settings. To disable port security on the Cisco switch interface, run this command at Cisco switch port:

no switchport port-security

Port security do a filter on MAC adress, number of MAC per physical port, you can expect many effects like loss of network connections on VM, VMotion troubles, unable to ping between VM on same switches…

LACP is not available on VSphere Standard Edition.

After a reboot of ESX, VM becomes orphan

Do a VMotion to change the Host, it will be recovered

If a VM is really orphan and you want to remove it, emtpy the host (except orphan), bring it out of the cluster and register it again.

You cannot change the timezone on the ESXi host.
The vSphere Client and vSphere Web Client automatically display time in your local Time Zone and will take into account UTC setting on host(s).

To set the time from the ESXi command line manually, use the esxcli system time set command. For example, to set the date to 31 Jan 2012 18:00:00 UTC, type this command as the root user:

# esxcli system time set -d 31 -M 1 -y 2012 -H 18 -m 0 -s 0

A datastore can be locked by a dump

~ # esxcli system coredump file list
 Path                                                  Active Configured       Size
 ----------------------------------------------------- ------ ---------- ----------
 /vmfs/volumes/Datastore/vmkdump/684938663845.dumpfile  false      false 1714421760
 /vmfs/volumes/Datastore/vmkdump/684938663233.dumpfile  false      false 1714421760
 /vmfs/volumes/Datastore/vmkdump/684938663533.dumpfile  false      false 1714421760

The output shows that I have 3 dump files which are blocking my datastore. Only the owning ESXi host can disable and delete them, so you have to find out which ESXi is responsible for each file:

~ # vmkfstools -D /vmfs/volumes/Datastore/vmkdump/684938663845.dumpfile
 Lock [type 10c00001 offset 200392704 v 10, hb offset 3875328
 gen 3, mode 1, owner 52ebd042-43b191f0-0173-005056871792 mtime 250
 num 0 gblnum 0 gblgen 0 gblbrk 0]
 Addr <4, 447, 0>, gen 1, links 1, type reg, flags 0, uid 0, gid 0, mode 600
 len 1714421760, nb 1635 tbz 0, cow 0, newSinceEpoch 1635, zla 3, bs 1048576

If the dump is active try to umount the datastore on every host one by one.

You can see the UUID from the ESXi host (esxcli system uuid get)that has locked the file. (Side note: The last part of the UUID is determined by the MAC address of vmnic0. 005056871792 = 00:50:56:87:17:92). To remove the coredump file, connect to the ESXi host with SSH and use the esxli system coredump file remove command. This will remove the configured active coredump file:

~ # esxcli system coredump file remove --force

vsantrace Removal vsantraced is also a potential datastore blocker. You can verify this by listing open files:

~ # lsof |grep vsantraced |grep volumes
34412 vsantraced FILE 3 /vmfs/volumes/c44fd830190/vsantraces/vsantraces--2014-02-28T12h36m36s899.gz

To remove the log, simply stop vsantraced, unmount the datastore and start it again:

~ # /etc/init.d/vsantraced stop

# Remove/Unmount Datastore

~ # /etc/init.d/vsantraced start

If you do not use Virtual SAN you can also disable vsantraced permanently:

# chkconfig vsantraced off

VMware vSphere 5.5.0 Update 2 and vSphere 6.0 hosts may experience multiple repeated disconnects leading to application outages in response to delays in completing heartbeat I/O. Content

A change was introduced in VMware vSphere 5.5.0 Update 2 and vSphere 6.0 to use Atomic Test and Set (ATS) by default for heartbeat I/O.

Due to the low timeout value for heartbeat I/O using ATS, this can lead to host disconnects and application outages if delays of 8 seconds or longer are experienced in completing individual heartbeat I/Os on backend storage systems or the SAN infrastructure.

To prevent VMware hosts on these levels from experiencing this issue, the following commands can be issued to disable using ATS for heartbeat I/O and revert to the 5.5.0 Update 1 heartbeat method. Note that after issuing these commands, the host will be required to be rebooted.

VMFS-3:

  esxcli system settings advanced set -i 0 -o /VMFS3/useATSForHBOnVMFS3 

(N.B. ATS for heartbeat is disabled by default with VMFS-3, so this command will only need to be issued if it has previously been manually enabled)

VMFS-5:

  esxcli system settings advanced set -i 0 -o /VMFS3/useATSForHBOnVMFS5 

For VMFS5 datastores: Run this command:

# esxcli system settings advanced list -o /VMFS3/UseATSForHBonVMFS5

You see output similar to:

Path: /VMFS3/UseATSForHBOnVMFS5
Type: integer
Int Value: 0                <--- check this value
Default Int Value: 1
Min Value: 0
Max Value: 1
String Value:
Default String Value:
Valid Characters:
Description: Use ATS for HB on ATS supported VMFS5 volumes

For VMFS3 datastores: Run this command:

# esxcli system settings advanced list -o /VMFS3/UseATSForHBonVMFS3

You see output similar to:

Path: /VMFS3/UseATSForHBOnVMFS3
Type: integer
Int Value: 0            <--- Check this value
Default Int Value: 0
Min Value: 0
Max Value: 1
String Value:
Default String Value:
Valid Characters:
Description: Use ATS for HB on ATS supported VMFS3 volumes

Storage VMotion fails with timeout

disable hardware acceleration on the specific ESX

Into advanced settings on the ESX, change the parameter DataMover.HardwareAcceleratedMove to 0, disabled

Then try again the move one VM at time !