I am comparing NetApp and EMC solutions for a VMware solution. The VMs will be on NFS. I know that EMC and NetApp use different methods of snapshots. Correct me if I am wrong on this, with EMC when a snap is made, all old data that is modified is written to hidden snap volume and the new data is written to the original location. With NetApp a pointer is put in the original data and the new data is written elsewhere. So with EMC there is a read operation and 2 writes, and with NetApp there are 2 writes although one of them will be small.
However though when it comes to reading that data, doesn't this mean that NetApp will have to make 2 read IOs to access the data, one for the pointer and one for the actual data? EMC will only have one read since the new data already replaced the old data. Does this sound correct?
Also from what my understanding is, with an NFS share EMC and NetApp will have roughly the same size usage by snaps?
Any real word experience with any type of performance impact having snaps of a file share running on an hourly basis for 2 days time would have with either system?