The EMC DMX would be for primary storage where the Centera would be for compliance, fixed content, archiving and retention among other uses. A more apples to apples comparison would be to compare the EMC DMX with the Fujitsu Eternus, IBM DS8000 as well as Hitachi (HDS USP and HP XP) storage systems. Other alternatives for primary open systems storage include EMC CLARiiON and Celerra, IBM DS4000 (Engenio/LSI), Sun, HP, 3PAR, NetApp, LeftHand, EqualLogic and ONStor among others. If your needs are for archiving and data retention based storage, in addition to the EMC Centera other solutions include those from or based on Archivas (HDS), Bycast (HP MAS & IBM MAS), IBM DR5xx and Nexsan among others.
In terms of performance characteristics and related technical comparisons take a look at the various vendors' websites of the above mentioned solutions. There are some benchmark data posted on the storage performance council (http://www.storageperformance.org/home) website that may be of interest, however keep in mind that before you go comparing different solutions based upon speeds and feeds, take time to understand your storage and application requirements and then align the applicable technology to those needs.
This was first published in January 2007