The good folks over in marketing made a sneak announcement on December 29th regarding the Disk Library for mainframe (DLm). Sneak because, lets be honest, how many of us had reading press releases as a high priority on December 29th?
In any event, there is some good stuff here. To revisit the core differentiator of the EMC DLm: this is a virtual tape library for mainframes that is not a disk cache. That is a significantly different architecture from either competitive offering from Sun or IBM--both of which are "merely" a small to medium size disk cache in front of a bunch of physical tape. Expensive disk. Expensive tape.
So EMC's approach is a little different: take the tape out of the equation. And a good chunk of the cost too. The DLm is far more than "just" a disk cache: by virtue of capacity and capability it enables you to store data more or less permanently on disk. Not to say that you will have no tape at the end of the day, but you will have a lot less than with other approaches.
So what did we announce? A new model, and some new features.
The new model is the DLm 4020. The 4020 is the little brother of the 4080, and can grow to a maximum of 64 TB in a single cabinet configuration. The DLm 4080 by contrast can grow all the way to 570 TB of disk.
Both DLm configurations are comprised of two key components, plus some additional infrastructure (switches, racks, etc.). The two big pieces are the VTEC--the virtual tape emulation controller--and an EMC Celerra for highly available storage and feature rich storage management. (It turns out, that at the end of the day, each virtual tape will be represented as a file on Celerra. Once we have each virtual object represented by a file, we can do a bunch of other stuff easily and transparently. Like replication. So this is a simple way of providing all kinds of really useful functionality without have to resort to some elaborate and mysterious architectural gyrations under the covers.)
In addition to the DLm 4020, the other news things with version 1.2 are:
- replication between DLm 4020 and 4080
- identical tape emulation on the 4020 and the 4080
- support for low power drives as an option
- increase in the maximum capacity of the 4080 to 570 TB
- an IRDC=FORCE option for emulated tape drives