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Not NAS, SAN or DAS but CAS

Feb 17, 20043 mins
Data Center

* EMC plays in the content addressed storage space

I tend to focus much of my time on software, and every now and then, I seem to forget (almost) that my neighbor EMC is still in the hardware business.  EMC is pretty good about reminding me though.  Take for instance what the company did last week.

It was EMC’s hardware event of the year, as it rolled out three Clariion CX systems, new Celerra NAS gateways, a Symmetrix DMX box with twice the power of its previous top-tier offering, and unveiled added capabilities to the often-hard-to-define Centera.

There seems to be much good news in all of this for existing EMC customers.  For Symmetrix users, there is more power.  For Clariion users, as well as the power boost there is also an opportunity to upgrade their existing Clariion systems to the new capabilities, thus maintaining the value of their current investment.  And network-attached storage lovers get a machine that comes both as a filer and as a gateway that can attach to a storage-area network and have other NAS behind it.  

The Centera has been a difficult machine for some people to understand probably because it is marketed as being neither DAS (direct-attached storage), NAS nor SAN – all of which are common acronyms at this point.  EMC positions it in the category of CAS – “content addressed storage” (also know as “content aware storage”), which is to say it is storage aimed at a particular type of fixed content, such as e-mail or a patient’s medical records. 

CAS is a new category and certainly a useful one.  It is surprising therefore that there are relatively few players offering related products so far, and an even smaller subset of that number who seem capable of articulating a compelling message to help users understand the value CAS can provide. 

In theory, CAS provides an environment that manages the way data is handled in terms of business issues, always including the issues of data protection, integrity of access, availability, data retention and disposal, and compliance with policies that result from regulatory requirements, industry expectations and the like.  Typically these devices will have lower-priced storage on them. 

EMC’s contribution to CAS at this announcement is that Centera for the first time is extending its CAS capability from being just an open systems tool.  It now supports mainframe environments as well, thus enabling the transmission of data between Windows, Unix and mainframe environments.

If all this seems to you like it fits well with Information Lifecycle Management (ILM), which we write so much about, you may score a point for yourself and leave work a half hour early.  Any of you still too blind to the importance that ILM will have in directing storage purchasing: stay after class and locate the whereabouts of three critical tapes from 1995.  Any three tapes.

If the topic of CAS is of interest to you, a few Web sites in addition to EMC’s are worth a hit, including Cambridge start-up Permabit ( and OuterBay ( 

Next time:  When it comes to storage, what’s up with Sun?