The unbearable lightness of being stateless
By hendel on Sep 05, 2006
Ever gone through an ascetic period of feeling better by owning less? The lightness of moving to college with just a couple of bags, quitting a job and selling most possessions. No entanglements, no commitments. This lightness is not about travelling light, suitcases come with wheels nowadays. And it is neither about a hermit without belongings, nor a surf bum with or without waves. It is about a martial artist that cannot be disarmed, because he is the weapon, the comfort of a possession that cannot be taken away.
Here is the test. Take laptop, keys, passport, passwords, checkbook, credit card, and wardrobe. Stateless is being able to function again within a day of losing them all. You pass the test if you don't need all that stuff, or can recover the loss in short order. If the loss is a big setback, welcome to the club, and to the quotidian stress of preventing the loss.
We are doomed by modern life complexities to only experience the lightness of being stateless for few yet memorable periods. But modernity also helps, through centralization, for example. Using banks and ATMs rather than stuffing currency in mattresses and wallets. Similarly for data. Service providers and employers help keep our electronic data in presumably safer places than laptops or digital cameras. Modernity helps statelessness by delegating the storage and protection burden to somebody else.
On the flip side, the stateless road warrior became an endangered species through the overexploitation of the laptop. Personal and corporate lives go with them in their hard drives. There is no lightness there, unless of course the laptop is used as a communication device rather than a storage device. A thin client that kept its diet except for some data caching here and there.
The crux is feeling as light as travelling with no luggage yet avoid the deprivation of owning nothing. The essence of being stateless is knowing that whatever we carry isn't critical to our functioning, or can be easily recreated. Bad things happen, and it is all about how fast we recover. Same for infrastructure computer systems, that is, the systems that centralize our funds instead of stuffed wallets, the systems that centralize our data instead of lugging our lives on a laptop, and of course the systems that provide the wireless network cloud so we can be stateless yet always connected.
Systems based on CMT processors, like the UltraSPARC T1 processor, or the just previewed second generation 64 thread CMT Niagara 2 processor, can be viewed as horizontal scaling within a chip. And soon they will become domainable with the introduction of "Logical Domains". These Logical Domains can also experience the lightness of being stateless. But what burden of baggage can these domains possibly want to shed? What entanglements and possessions is a server stressed out about? The burden is the I/O, the data stored in disks, the observable behavior over network attachments, and the idiosyncracies of a modular I/O architecture. Without all these, servers are carefree souls.
The liberating part of Logical Domains is precisely that one can create surf bum domains that do not own any I/O, and in fact most domains in a CMT system will not own any I/O. These are not hermit domains crunching numbers away in seclusion, they are rather domains that rely on somebody else for I/O. They delegate the burden of I/O bus ownership, probing buses for devices, loading device drivers, and recovering when bad things happen; as they do happen. Applications and services can be hosted in multiple such stateless guest domains. And when bad things happen to a guest domain, they get back on their feet really fast, because they have no I/O bus topology to probe, and no I/O devices to initialize.
Early into this CMT blogging thread we claimed that a CMT system can mimic the attributes of discretely deployed horizontally scaled systems, now with Logical Domains it can surpass the master. It can sustain guests that lead an I/O stateless lifestyle. Every day.
Logical Domains are coming to SunFire T2000 and T1000 Servers among others. The free SunFire server trial program is in perfect harmony with the lightness of using a server without really owning it, let alone the path to Nirvana through sharing the details of some impressive use of the box.