Virtualization VMWare

Thin vs Thick: VMFS formats.

This took me a little while to get my head around the concepts.

But here is my understanding:

Thin In this particular format, the of the VMDK file on the datastore is equal to the amount that is used within the VM itself as it zeros out the space prior to I/O being written, so for example if you create a 200GB virtual disk, and you populate it with 100GB worth of data, the VMDK will be 100GB in size and will grow as more data is added to it.

Thick The VMDK file on the datastore is the size of the virtual disk file that you provisioned but no prezeroing takes place like it does in thin format.  So for example if you create a 200GB virtual disk and write 100GB worth of data to it, the VMDK will still appear as 200GB in size but only contain 100GB worth of data.

Eagerzeroedthick The “truely” thick virtual disk, the size of the VMDK file within the datastore is equal to the virtual disk size that is provisioned. If you create a 200GB virtual disk, and write 100GB worth of data the VMDK will be 200GB and contain 100GB worth of data and 100GB of zero’s. Which format is the best? There are pro’s and cons for each. Thin format requires more monitoring and cant be used with RDM’s where Thick/Eagerzerothick are not as efficient as thin and one might not see as much space savings when implementing this type.

Virtualization VMWare

Enabling SSH and SFTP on ESXi 5.x Host

So I had just built a ESXi 5 VM when I wanted to upload some ISO’s into a datastore, alas SSH is turned off by default in ESXI 5

So, first part is to turn it on, you need to be physically at your ESXi box in order to do this part.

At the ESXi console screen

Logon using the root account

Select “Troubleshooting Options” from the menu

In the next menu, select “Enable SSH”, you will notice that it says ‘Disabled’ in the right hand pane

Press enter to change to enable

Thats it!, you can now quit out of there and go onto the next part which is to get the SFTP server running, truth is it is missing by default in ESXi 4

So lets get it

ssh into your esxi box using the root account.

cd /sbin */ Changes to the right directory
wget */ Downloads sftp-server files
tar xzvf sftp-server.tar.gz */ Extracts file into current directory /sbin
rm sftp-server.tar.gz */ Removes file now that we have extracted it

Log out.. Thats it! You should now be able to SFTP files to and from your ESXi 5 host!