VMware crashes after updating (upgrading) of host OS (to CentOS 5.4)

If you have in your hostd.log something like this:

Nov 07 21:19:12.648: Worker#23| Caught signal 6 -- tid 31543

this can be related with update(upgrade) of host OS.

After upgrading of a host OS (CentOS 5.3->CentOS 5.4) I got an issue - a guest OS started to crash. Searching around for a possible cause I found bug post in CentOS bug tracker. Seems that issue is related to glibc update (last version is glibc-2.5-42) and a fix is to downgrade to previous version on host OS (glibc-2.5-34).

To be sure that your downgrade of glibc worked - check the size of libc-2.5.so. I got an issue on downgrade (even with --oldpackage rpm was not willing to replace a libc), and that's why I lost some hours trying to figure out what is going on. So, be sure to check the size of the files after downgrade. It can save you some hours :)

VMware troubles

Well, I'm not a hardware guru, but from my experience I figured out the following:

Dell Servers + QLogic HBA + IBM Storage = troubles

Dell Servers + Emulex HBA + IBM Storage = working ok

Dell Servers + QLogic HBA + EMC Storage = working ok

Other one issue is:

Any server + Any HBA + Any storage - Fiber Channel Switch = troubles (unclean filesystem on Linux guests with EXT3 filesystem)

ESX host not connecting to Virtual Center

We got following problem some days ago:

One of our ESX (version 3.5) hosts, after crash, was not connecting to Virtual Center (version 2.5).

Solution:

• Restart management service on ESX host

service mgmt-vmware stop

service mgmt-vmware start

• Restart Virtual Center service on Virtual Center server (stop/start on service VMware Virtual Center in Services)

One more stuff - if you have a lot of memory on your hosts (16 GB or more) I would recommend you to increment amount of console memory on your host to 800 MB. You can do this in "Configuration" tab for host in your Virtual Center console.

Creating a copy of the disk (vmdk) in VMware

When you need to have the a copy of the disk from one VM on the other:

• Power off  source VM, copy your .vmdk files to destination VM (probably you would like to change disk name and flat name - just rename your files and edit smaller .vmdk file to set correct name for flat file).
  
• Set new UUID for your copy of your original .vmdk file

/usr/sbin/vmkfstools -J setuuid path_to_destination_VM/filename.vmdk

• Add new disk to your destination VM (using "Use an existing virtual disk" option)
• Start your VMs (source and destination)
• Mount new drive on your destination machine

We used this solution to make a quick copy of data files disks from primary Oracle server to standby Oracle server.