In early 2015, a fairly large new client of ours – a 100-strong company of architects based in London approached Nittygritty in desparation for advice and a second opinion, having been failed by their previous IT professional (a highly talented consultant, judging by the string of acronyms after his name). He was asked to architect a brand new system as a replacement for their ageing VMware/Equallogic system.
The consultant recommended a (supposedly) very low-cost system consisting of four Dell PowerEdge R730 servers and two Dell PowerVault MD1400 disk arrays leveraging Microsoft Storage Spaces and Hyper-V. The client purchased the hardware and the consultant embarked on building the system. Despite urgency (the old system was long out of warranty, chronically out of space and everyone was almost too scared to touch it, it was so unpredictable!) weeks went by as the system design was evolving but nothing was actually materialising.
By Greg Karas, Sr. NGneer® 18th January, 2017
When we came on board, we found a very expensive set of servers acting as room heaters but no sight of a working system. Since we had not previously worked with Storage Spaces, a relatively little-known feature that Microsoft introduced in Windows Server 2012, we began by studying and analysing the design.
Storage Spaces makes use of common inexpensive components to achieve what is traditionally provided by (more expensive) specialised SAN hardware. As with any IT systems though, there are system requirements that must be met for a given solution to meet expectations. What was purchased did not include some important hardware components to meet the requirements in terms of performance (lack of write cache causing slow writes) and in terms of redundancy (a minimum number of disk arrays required to ensure enclosure redundancy is three, otherwise there are inherent single points of failure intolerable in a SAN system).
We were faced with a very difficult task of convincing the client to abandon the original design in favour of our well tried and tested system based on Dell PowerVault MD3420 array, with an additional investment in cost. The client was diligent and spent the time needed to explore a number of different avenues, talking to other consultants, and eventually to Dell directly, before arriving to the conclusion that our recommendations were sound. As soon as we got the okay we began work and implemented the system within days.
Lessons learned:
Today our clients are very happy owners of a robust system built and maintained since 2015.
(I recently found the two MD1400 arrays still sitting in their boxes, hidden under the table like a naughty dog)