Snapshot and VMDK Process

[jbp00007]

I am having a ESX 3 with 15 of VMs on it and connected to Fiber SAN.

I divided my SAN to different storage group and configured it in ESX.

I installed some VM Ware patches last sunday after Powering off all the VMs and rebooted ESX.

1) But 3 VMs (Win 2003) in a VMFS volumes (or on a same Storage Group) are not powering up and when I looked that volumes only has 4GB space free from 100GB. I am wondering how much free space needed to powering up VMs?

When I added 25GB space all three started purfectly without any problem.

2) During above problem I was wondering Snapshot is using more space in these all VMs so I deleted snapshot on my one of the running test VMs (Snapshot taken 6 months before) but that brought down my test VMs and locked VMDK file in some process which I was not able to use in NEW VMs. I means I can configure new VMs with existing VMDK but it was not powering up VM. So I power down all VMs and restarted ESX and then use existing VMDK and then only able to power up new VM.

I have two question if somebody can answer please.

1) What is the usage of Snapshots? and Why it changes VMX file after Snapshot to use XXXX-000001.vmdk file as SCSI0:0 filename in XXXX.vmx file.

2) Which process locked VMDK file and how to kill it without restarting ESX host?

I will appreciate if you can use you expertise in these?

Thanks

[esiebert7625]

If you are not using memory reservations then a vswp file is created equal to teh size of memory assigned to a VM. So a VM with 2GB of memory will create a 2GB vswp file, if it cannot create this the VM will not start. If you add a memory reservation to the VM then it will create a smaller vswp file. A 2GB reservstion will result in a 0 byte vswp file, a 1GB reservation will result in a 1GB vswp file. It's best to not make your reservation the same size as the assigned memory otherwise page sharing is disabled for that VM. I set my reservations equal to half the VM's assigned memory.

Snapshots can grow up to the size of the original disk file, how fast they grow depends on how many changes are made to the original disk file. When you take a snapshot it stops writing to the original vmdk file and creates a delta.vmdk file with all changes. Once you delete the snapshot all changes are written back into the original vmdk file before the delta files are deleted.

Snapshot disk space and growth - http://www.vmware.com/community/thread.jspa?threadID=85409&messageID=649362#649362

What is a snapshot - http://www.petri.co.il/virtual_vmware_snapshot.htm

Beware the long snapshot - http://www.vmwarez.com/2006/11/beware-long-snapshot.html

Fyi…if you find this post helpful, please award points using the Helpful/Correct buttons.

-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=-=-=-=-

Thanks, Eric

Visit my website: http://vmware-land.com

-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=-=-=-=-