You may encounter this error on VMware ESX / ESXi server on a guest event console (on vSphere Client) :

Error message from host.domain.tld: Failed to connect ethernet0

Of course, the guest system have no functional network.

This probably happen if you actually rename a Virtual Network that was previously used by the guest. Changes does not apply automatically on guests.

To solve this, simply do :

- Go to Summary tab > Click on Edit settings
- Click on Network adapter 1 > and select the proper Network label inside the Network connection section.

Got this error trying to adjust time on a VPS from the host node?

[root@server ~]# vzctl set 111 –capability sys_timen –save
Unable to set capability on running container
WARNING: Some of the parameters could not be applied to a running container.
Please consider using –setmode option

There is two possible solutions :

1. Stop the VPS and use the following command and start the VPS :

vzctl set 111 –capability sys_timen –save

2. Use this command and the the parameter will be enabled next time the VPS will be rebooted :

vzctl set 111 –capability sys_timen –setmode restart –save

* Be careful with option 2 – VPS reboot itself in some occasion using this command!

Using VMware Server on RedHat Enterprise Linux, you may expect this error in log file /var/log/secure :

PAM unable to dlopen(/lib/security/pam_unix2.so
PAM [error: /lib/security/pam_unix2.so: cannot open shared object file: No such file or directory]
PAM adding faulty module: /lib/security/pam_unix2.so

Actually, this error does not seem to affect the functionality of VMware Server. To work around this situation and get rid of this error, let’s create a symbolic link like this :

ln -s /lib/security/pam_unix.so /lib/security/pam_unix2.so

(must be done as root – or sudo)

VMware Server performance can be improved in so many ways… there are some recomendation that I’ve discovered when I was using this product at large before moving them to ESXi :

• Use preallocated virtual disk
• Use as less virtual hardware as possible – do not add unneeded hardware
• Use ext4 or XFS filesystem (if host run under Linux – be careful with XFS, does not react so well with power outage!)
• Use fast enough hardware (depending on your usage – have as more ram you can afford and avoid host and guests to swap!)

Avoid unused memory to be reallocated to the host, this consume a lot of CPU power.  Since VMware Server 2, this option has been removed from the GUI. You need to add the following parameter in the virtual machine config file (.vmx)

MemTrimRate = “0″

Set the following filesystem attribute (edit /etc/fstab) to save on disk I/O (on host as well on guests) :

noatime

Example : LABEL=/     /     ext4     defaults,noatime     1 1

Use the following kernel parameters for linux guests (the first parameter is to solve the known time synchronization problem) :

divider=10 noapic nolapic

Do NOT add a second virtual CPU if you are running VM on a single socket machine. Multiple core CPU does not count… enable this only if your motherboard have two physical CPU.

In such case, and you probably running a modern Linux distribution with a stock kernel, you should disable the SMP function… just add the following kernel parameter (/boot/grub/grub.conf) :

nosmp

VMware allow four type of virtual disk (vmdk) :

0 : single growable virtual disk
1 : growable virtual disk split in 2Gb files
2 : single preallocated virtual disk
3 : preallocated virtual disk split in 2Gb files

command : vmware-vdiskmanager -r <source-disk> -t <type> <target-disk>

Now, if you want to convert your growable disk into preallocated disk, you may use the following command in a terminal :

vmware-vdiskmanager -r current_disk_name.vmdk -t 3 new_disk_name.vmdk