For many businesses, using thin provisioned volumes is best way to optimize a virtual machine environment. This can be applied at both the hypervisor level and both the storage area network level. In the case of VMware and EqualLogic (EQL), although both can be used in conjunction with one another and both will continue to grow together, however when space is cleared up, VMware does not report to the EqualLogic when freed blocks can be returned to the free space pool. This can cause an EqualLogic volume to appear to be using more space than is actually in use.
VMware shows that 414.59GB of free space is available.
EqualLogic shows that 272.09GB of free space is available.
One of the few ways this could be fixed was by migrating all virtual machines to a newly created datastore. This process could be incredibly time consuming and add a large load to the environment. Fortunately, from EqualLogic firmware 6.0.1, space can now be reclaimed on the EqualLogic by running a few simple commands in VMware.
Enable SSH on a VMware Host
The first step will be to enable SSH on a host that has access to the Datastores.
Select Configuration
Click on Security Profile
Find SSH in the menu and start the process.
Reclaiming Space on the EqualLogic Volume
Note: You must be on firmware version 6.0.1 or higher to be able to reclaim disk space.
Once SSH has been enabled, connect to the host using SSH. Putty is a great free resource to use. http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html
Run the command
cd vmfs/volumesNext I typically browse the directory to select what datastore I want to connect.
Run the command
ls
In this case I have identified that I want to clean up EQL-Vol-01 (this is case sensitive), so next I issued command
cd EQL-Vol-01Although I have successfully navigated to /vmfs/volumes/EQL-Vol-01, VMware will navigate me to the ID for the datastore so my path will display something a bit different.
I typically verify what commands I am going to run before running them so I ran the command
vmkfstools –y ?
Next, run the command
vmkfstools –y 60
This will clear up 60% of the amount of free space available. Although you can increase this number up to 99%, VMware suggests keeping this at 60%. If need be, the command can be run multiple times to reclaim all the free blocks. If the command fails, lower your percentage to something like 10 or 20%.
If Group Manager was open while the free space reclaim command was executed, Group Manager will auto refresh after space starts to clear up on the volume. In the example below, it took about 60 seconds to refresh that 50GB of space had been reclaimed.
Resources:
about Thin provisioning of Equallogic and vmware vSphere, http://en.community.dell.com/support-forums/storage/f/3775/p/19411388/19966452.aspx. Accessed April 28, 2014.