They work differently and can be used together.  One key thing to realize is that with EQL Thin provisioning, the in use space shown on the array GUI will only go up, never down.  The array can record space used, but when a block is freed, the array isn't notified so it can't be returned to the free space pool.  ESX will have no awareness of the thin provisioning on an EQL volume.  In the future both ESX and EQL will support a new standard for SCSI called UNMAP.  So the server will allow freed blocks to be returned to the free space pool.     Thin provisioning on the ESX side is not visible to the array, however since it's controlled by the OS, free space is returned to the VMFS volume free space.   The only caveat I've ever heard with TP on ESX side is possible impact to performance of VMDKs during writes, when the VMDK has to be expanded.   Especially in ESX v4.x, that requires an exclusive reservation on the entire VMFS volume in order to allocate more space to the VMDK.    So on an higher end server you might want to forgo the TP option in ESX.   The array preallocates a small amount of space as a buffer on TP volumes to stay ahead of new writes.     Regards,   -don 
Hi all, Both Equallogic and vmware vsphere have Thin provisioning feature, and my question is that if I run vSphere on equallogic, which Thin provisioning shall I use? I know there is no necessary to adopt Equallogic and vSphere's thin provisioning at the same time. I guess maybe equallogic's thin provisioing is better, because it is based on hardware, but I am not sure. would you kindly give me some suggestion? Thanks    
about Thin provisioning of Equallogic and vmware vSphere