The Storage Economist

Well there has been lots of exciting new from HDS and our worthy competitors the last few weeks on high-end architectures, clouds, virtualization, etc. While this is important to note, I’d like to focus my next few blog entries will be on a more basic storage architecture, Direct Attached Storage or DAS. Many people have forgotten the olden days, pre-SAN, when direct attach was the one and only storage architectures. There seems to be a renaissance in relation to DAS, especially in the cloud architecture space.

A recent article from Forrester analyst Andrew Reichman was a significant reference point on this topic, as he poses the question as to whether we need SANs anymore. Without a comprehensive review, I do agree and disagree with some of the findings.  Where he is right with the indictment on SAN:
•    Stranded capacity still exists on the arrays
•    Tiered islands has continued, with larger and larger islands of disparate capacity
•    Some micro optimization (10-20:1 host to array ratios)
•    High costs of SAN overhead
•    Relatively poor utilization still
•    Provisioning time is still too high

But are these shortcoming the fault of the SAN and the transport architecture or the underlying storage architectures?  Some areas of DAS deficiencies that have been addressed with SAN and basic storage architectures are:
•    High performance
•    Better availability, data path and the storage array
•    Scalability
•    Consolidation
•    Remote boot
•    Server-less backup
•    Data mobility
•    Better DR
•    Central command and control

There is much to discuss about SAN and DAS architectures – for a quick overview I will refer you to a webtech seminar from Hu Yoshida on the tech differences of SAN and DAS, and more specifically how advanced storage architectures have filled-in on some of the SAN deficiencies that were promised a decade ago. That webinar (recorded last week) is available here.

My own interest tends to be in the economics of DAS and SAN. I have an upcoming webcast on ‘SAN vs DAS, a TCO Perspective’ and it is scheduled for June 10. You can register on-line here.

The next post installment will focus on one element of the economics of these architectures – Total Cost of Acquisition or TCA. Subsequent posts will deal more with the variations of TCO costs. But in case you cannot wait….

TCA Outline
•    DAS is cheaper than SAN at the unit level
•    SAN can have a very high overhead cost (HBA, path mgmt, Switch, ISL, directors, SAN SW, cables, cable and patch panels) when amortized by port
•    Short stroking and other techniques are often used to squeeze better performance on DAS
•    Growth rate will have an impact on DAS TCA
•    Where is the cross over point in terms of total usable capacity where SAN is lower TCA than DAS

TCO Outline
•    Cost of performance as a factor
•    DR and data protection costs
•    Cost of management, encryption
•    Costs and effort for provisioning
•    Thick vs. Thin
•    Power consumption per usable TB
•    Migration, end of life costs to retire assets
•    Use some of the key 33 types of money to create a comprehensive TCO analysis: TCA, lMaintenance, Power, Space, Cooling, Cost of waste, Provisioning time, Total estate, Admin, DR Protection, BAckup, Archive, Migration, ILM