The most recent version of code for the VNXe requires 205% protection space for all resources that are densely provisioned. Thin provisioned resources can reserve down to 5%.  Destinations should be configured with the same protection space as the source, to prevent the destination from running out of protection space before the source. Also, during a failover, you want to be sure the failed over destination won't generate more changes (in the form of snaps) than your source can accommodate when you try to failback.  The UEMCLI should not permit the user to bypass VNXe's best practices that are enforced by the GUI interface. Thanks Ambrogio for point that out, I'll make sure that is fixed in the next release.  For VNXe iSCSI, and similarly Celerra iSCSI, the production volume and protection space are shared. VNXe's current best practices of 205% are in place to handle cases where the user doesn't create snaps frequently and has a high rate of change. If the user fully writes every block on the Vdisk, then snaps, that snap will consume 100% of the Vdisk size in protection space. Then, if they rewrite the Vdisk again and attempt to restore to the snap, the restore operation creates a temporary snapshot (which would be another 100% protection space). This would immediately fail if we didn't require at least 200% protection space reserve, preventing the user from actually using their snapshot.  Reserve space recommendations of 205% and 235% are based on a 5% daily rate of change. The 235% is suggested when you have a snapshot schedule configured, which would retain snaps for 7 days by default.  Replication destinations also require 205% protection space for densely provisioned Vdisks. When using Replication Manager, a failover includes performing an iSCSI restore and could hit the same scenario described above.  In a future release, VNXe's best practices have been adjusted to permit 105% protection space for all iSCSI resources (both densely provisioned and thin provisioned). This can be achieved safely due to added safeguards in place preventing snapshot creation that would otherwise jeopardize the production Vdisk's reserved space or prevent restore operations.  Hope that helps. Tyler
Hi,  I need your help to find any document that talk about the large amount of space that the protection storage size on VNXe is taking - 205-235%, I keep getting complain about that, that EMC is a space eating  I know that I can work with thin provisioning  and to sign less space but its hart my performance.   I am trying to understand the reason why in a ISCSI LUN I need 205% space for the protection storage, which means that if I have a production ISCSI LUN with 1TB space, I need to reserve 2TB of space for the snaps, that give me a total of 3TB space for this ISCSI LUN with the protection  I know from before that it was only 105% on the celerra, but the change to 205% is not clear for me.  can you assist me with it?
protection storage size on VNXe