"the X-bricks have to have uninterruptible power supplies (USB) in case a controller goes down"
Do you mean UPS and not USB...
EMC’s XtremIO array has been launched into general availability today. Its details are as we said here and the storing of metadata in memory is key to understanding its speed. Data is stored in 4K blocks with each block having a unique hash address. There are two levels of addressing in the metadata. First an incoming data …
Based on their press conference there are many things they don't have.
Scale-out is a feature set that is coming. You can only buy 1,2 or 4 brick unit.
You cannot buy a 2-brick unit and scale-out to a 4-brick unit at launch.
The metadata is in memory - UPS failure indicates data can be lost if the controller(s) fail.
Hot-Spare technology is limited - and RAID is distributed across all SSDs. Indicates Raid Rebuild is felt across all SSDs in use.