Compellent's C-Drive event last week drew about 300 storage administrators and IT generalists to downtown Minneapolis one week before EMC World. While that's small show by EMCWorld standards, it was a big event for Compellent customers.
I have yet to meet a more evangelistic group of storage users. Compellent's architecture creates a unique storage management environment. While the architecture supports a variety of RAID levels and RAID-based array configurations, one has to leave pre-conceived notions regarding management and functioning of traditional RAID arrays at the door. These people behave as if they had seen the light and will never go back to their old way of doing things.
During an evening gathering, one user looked at my ID badge and asked point blank what a storage industry analyst does. After some back and forth, he challenged me to recommend Compellent to all my user clients and went so far to suggest that not doing so was a dereliction of my responsibility. Yikes. I checked his badge more than once just to make sure he wasn't a company man.
As is typical at vendor-sponsored user group sessions, customers get to rub elbows with product designers and company executives. For vendors sponsoring these events, the interaction can be a double-edged sword. Engineers and product managers who conduct education sessions get to hear both the good and the bad news in public.
These sessions were no different, and some of the issues raised were not unique to Compellent and worth noting for other users planning to implement automated tiered storage architectures (3PAR Autonomic Storage Tiering, EMC FAST, IBM Easy Tier, etc.). Compellent's subsystem OS called Storage Center directs all writes to the highest performance storage tier within the subsystem--RAID 10 disk or SSD when installed--but will demote a recently written-to volume to a lower tier afterward based on user defined policy. This can make the most efficient use of the most expensive high-performance disk tier. However, one user had discovered a service level agreement (SLA) negotiated by a previous administrator with a database user group that mandated RAID 10 storage for that particular application. The agreement made no distinction between disk reads and writes, nor did it address the placement of active vs. dormant volumes.
I suspect that there are similar SLAs out there and that automated tiered storage will break them. The experience of Compellent Storage Center users can be instructive. Be prepared. If as a storage administrator you encounter a Compellent customer and have automated tiered storage on the roll-out road map, I suggest striking up a conversation.