This week randomly I found out that one of the hottest topics of the IT industry at the moment “Stateless Computing” had no reference in Wikipedia. WTF, who is updating that wiki? So, for the first time I added the term to Wikipedia. http://en.wikipedia.org/wiki/Stateless_Computing
Reading about stateless computing and following some twits on twitter I noticed that there is no real consensus on where the statelessness starts and where it ends. In one of the discussions I said:
@andreleibovici "software statelessness" OK I’m intrigued. what do you mean? example? use case?
bradhedlund: UCS might be statess hardware computing but you r booting ESX that is in specific state (statefull). True stateless computing would have…
bradhedlund: the software component without any state. ESXi as an example. However w ESXi without state (embedded as example) u lose updates after reboo.
bradhedlund: Does that make sense to you?
andreleibovici: If the OS (ESX) is on the SAN, and the blade is booting from SAN, why would it matter if the OS is stateless or not?
bradhedlund: Agree, but that would b true stateless computing. No boundaries 4 the stateless technology. Anyway, this is my opinion.
bradhedlund: Perhaps 1 day we’ll b able to carve d LUN & deploy OS using service profiles.
U can define service profile & deploy OS w/ BladeLogic today. Carving LUN at the same would be cool, were not too far away from that.
In summary, stateless computing today is only applicable to hardware while the software and application stacks are in a defined state (ex. installed and configured, pre-carved LUN).
Until the day that whole computing stack (hardware, hypervisor, application and storage) are fully capable of provisioning themselves based on workloads or a service profiles there is not true stateless computing.
Some are a little bit more pragmatic and would say that there is no such thing as Stateless Computing. I just matter of where the state is actually stored.
I have to admit thou that some efforts are being done in the automation space to overcome the lack of technology and integration between services, hardware and vendors. Even thou some technologies would say that automation is not statelessness.
RT @scott_lowe: @andreleibovici I don’t believe that ESXi PXE boot is the same as statelessness. We are exploring options… < Concur
Where does the truth lies?