Each time you provision, VNXe allocates chunks of storage to an SP. These chunks are not necessarily the exact size the provisioning request requires, it is sometimes more. This extra space is not lost, but it is only available to the SP it is assigned to. When this happens, the two SP's will return slightly different amounts of available space for a given pool.  Depending on the types of drives and number of drives in your system,  the discrepancy will be more or less obvious. Using NL-SAS and/or having large numbers of drives will cause the system to increase the size of the chunks.
Hi,  I have a 3300 configured with 2 ISCSI servers, one on  each SP and on a separate IP address range. Roundrobin is configured in ESX and the ISCSI servers are isolated in VLANs. All is working ok and can see 2 paths in ESX.  I am observing that when I create a new Datastore I have the option to select ISCISERVERA or ISCSISERVERB for each Storage Pool. Say for example the Storage Pool is 3TBs, both read available space as 3TBs. I select one ISCSISERVER e.g. A and create the DataStore of 1TB in size.  When I go back into create another DataStore the available space is not evenly distributed between the two SPs. The are not reporting that they see the same amount of available storage for the storage pool.  Can someone explain this behaviour please?
VNXe Storage Presentation