Sims and Servers...WHAT!!??

Recently Susanne Pascalle started a thread entitled "How to find class of sim", now I haven't a clue how to answer her question but was fascinated by the question and the responses...hence this thread.

As someone who is within hours of arriving at the 27 day mark and hence finally within reach of some realistic land buying cash, I thought I had it pretty well sussed as to where the best land deals were..after all I've spent most of the last three and a bit weeks looking at majestic hills and beautiful bays vanish before my eyes behind examples of 'interesting' architecture.

So there I am down to my short list..and then Susanne lobs her question in front of me...

Could I ask someone 'in the know' (and I suspect there's quite a few..) if they could possibly explain all this stuff about sims and different classes of servers because I have the feeling it just might be important to know this before I - and anyone in my position - buys.

(Sorry if I sounded a little sarcastic there Susanne, I really am VERY grateful for seeing your thread, and to anyone who could help)

Basically, the newest (and fastest and most reliable, apparently) servers are Class 5, which is why you will see them being referred to.

As you go back onto older servers, there may be either four, three or even two sims being hosted per server.

Stands to reason therefore than the older server based sims are not as squeaky shiny and lag free as Class 5. Apparently.

As I understand it, there are 3 classes of servers in SL there days, class 3, 4 & 5. Class 3 servers are the oldest and class 5 are the newest. Obviously, the newest servers take advantage of newest technology, although I seem to remember a thread a while back where techie types had clocked speeds and determined that there really wasn't much gain between a class 4 and a class 5.

So for your purposes, this only really matters if you are looking at land on estate sims. Class 4 estate sims will not have voice capabilities and class 5 will. If you are looking at mainland, then it is all irrelevant since voice will be enabled by default on all sims regardless of class.

Finding a sim without "interesting" architecture is very difficult on the mainland since there is no zoning, if your interest is in a more controlled environment, you should probably look at estate parcels with covenants.

Servers are the hardware that the simulators are run on. Simulators are what run a region instance. They can comprise of multi-cpu and/or multi-cpu - multi-core set-ups. The oldest class of server that *may* still be in use are Class III hardware which was defined as a dual-cpu, single core set-up (1 sim instance per CPU, 2 sims per server). Class IV Hardware were AMD Athlon 64-bit Dual-Core, Dual CPU servers (2 sim instances per CPU, 4 per server). Class V hardware (the latest known/newest configuration) are Intel Pentium Xeon Dual-Core, Dual-CPU servers running in the same configuration as the Class IV hardware. The Class V servers have been noted for running better under heavier script loads.

Hope that answers some of what you are seeking.

Here was that post about class 4 vs class 5

/111/14/164590/1.html

Class 5's are not "less laggy" since most lag comes from the stuff you put on it, not the actual server hardware. A brand new sim will have very little lag until people start building on it and loading it up with scripts...

Yep.

Hence the 'apparently'. : )

?BUT?
If a sim is sharing hardware and bandwidth with one or more other sims, then an empty sim could still be laggy because one or more badly cluttered sims with high avatar counts in the same box are hogging the box bandwidth?
Unless a fixed proportion of the all box resources and of network connection bandwidth are dedicated to each sim, then lag is a lottery. Even with best practice on the part of the builder and the visiting avatars, lag due to sim hosting will vary randomly for an individual sim.

Does anybody know how server resources are allocated?


I do realise that once 'out of the box', traffic has to run the general networks gauntlet,. However if it's lagged to begin with ......

Sling, this thread will answer some of your questions, but the people who really know this level of detail usually hang out in the Technical Forum....

/111/1f/106305/1.html

Tks for that, but I was already aware of most of the issues to do with minimising lag in a sim.

The intended thrust of my comment/query was to do with the question here of a sim being more or less 'laggy' on one class of a server than on another.
The answer appears to be that a sim hosted on a theoretically 'superior' class could be far more laggy than the same sim on a theoretically 'inferior' class - due to the sharing of server resources with one or more lag-monster sims running in the same box.

It is probable that scripts might run faster on a Class 5 server, but that might be the only advantage.
However, if someone is not interested in Voice on an island, a Class 4 server might be a better option. This because Voice could be bandwidth intensive. On a Class 4 server, you wouldn't have to worry about the extra load imposed on the box by high-traffic Voice-enabled sims sharing your server.


It's all a bit moot anyway.
Laggy like hell all over tonight. Friends online borked, etc. *sigh*

Okay that all makes perfect sense. As I understand from what everyone has just said..the oldest areas of SL (the oldest sims) are powered by the oldest servers and the newest sims by the newest and (supposedly) more advanced servers (the older servers are older technology and slower than the newer..in theory).

I guess at this point, this and Susanne Pascalle's thread just crossed paths..how do we tell the old from the new?

Bizarrely the answer to that question may be revealed from a thread I posted a few hours prior to this one regarding 'maps of SL', one response came from Livinda Goodliffe who posted the url address of a map:

http://www.aiai.ed.ac.uk/~bat/sl/map.html/

This shows an older SL and therefor presumably the older sims and older servers. It seems to me it would be interesting and probably useful to get some idea of the evolution of SL through time so as to pin point the older sims. Does anyone know if there is any way of identifying the age of a sim - other than searching for archive maps of SL.

Not necessarily. Servers are upgraded as they fail, so older regions could be running on brand spanking new hardware.

Also, i seem to recall that Class 5 servers have more RAM, and not just because they have for sims running on them, but there would be more memory available for each sim.

Another brilliant theory bites the dust......

Just wanted to point out that Pentium 4 and Xeon are two completely different CPU's.

Not that it's anything really relavent other than to just nit pick over, but you are correct. For some reason I have a bad habit of lumping that in there when I type "Pentium". I still want to type Intel Pentium C2D when I talk about the proc in my rig now when really Intel is just calling them Intel Core 2 Duo's. It also has to do with the fact that I have been dealing with Xeon's Since the P2 and P3 Xeon's, which were indeed a Pentium II Xeon and Pentium III Xeon. The 32-bit Xeons of recent past were still based on the P4 core, still a P4 in my mind.

Really wasn't trying to nit pick you... was kinda confusing, that's all. In case someone wanted to really know exactly what's in there

The bottom line is just because the land seller telly you it is a class V sim, does not mean it is, or will stay that way. The way LL designed the sims they are all running on a dedicated CPU. Some are just on a multi-cpu syste. Linden Labs does not give any way to tell what type of server you are on anymore.

The breakdown according to a post from LL is as follows...

Class2 hardware (1CPU, 1 sim)
Class3 hardware (2CPU, 2 sims)
Class4 hardware (4CPU, 4 sims)
Class5 hardware (4CPU, 4 sims)

As crashes occur, sims seem to restart on different hardware. I have not been able to see a pattern for this. A brand new sim is definatelly on a class 5, but there is no guarantee that it will stay that way, no matter what anyone my say.

Class 5 servers basically diff then class 4 servers other because of the extra 2 giga of memory.......other then that there is no real improvement.

Please stop saying that.

If a sim is on a class 5 server, it will not restart on a class 4 or any other kind of server. When they come out with class 6 hardware, it won't restart on one of those servers either.

From /139/67/152713/1.html


For those interested in class 4 vs class 5 hardware, Ian Linden said in http://blog.secondlife.com/2006/10/16/looking-forward-to-class-5/ :

Anyone dealing owning etc a Class 5 server will tell you failure still occur. Whats worse is teleports, restarts etc don`t always work. There are many 5 class server owners/rents will tell you if your sharing your server with a highly dwelling partner you are in deep poo!.

In your quote you confirmed what I was trying to say, There is no guarantee what class your sim is on. It was stated, it will come up on the same class "unless someone specifically changes the definition of your region". Therefore it is not impossible.

I suspect that estates are unlikely to ever change sim class, but mainland class changes will be entirely at LL's discretion. Some of that information dates back to last fall, and a lot has changed since then.

I attempted to get this question answered 4 moths ago and the final response I received was that there was no way to tell what class any particular sim is running on at any particular time. I wish I had held onto that message now, but I did not worry about it any more.

In any case, I would not worry that much about class. A sim is one CPU no matter what class the server is. I suspect they all run about the same, and after watching ours move around I have found that the 'neighboring' sims have more impact that any class changes would. Any guarantees anyone gives you as to what class you are buying wil be guesswork on their part, and subject to change at any time LL chooses to change server allocations.

Your analogy is incorrect.
Neither the Class 4 or 5 have 4CPU's, the class 4 has a single CPU with dual cores, the class 5 has 2 CPU's both with dual cores.
Each sim is run off a single core.

What is relevant is not the cores/cpu configurations, it's the shared resources, ram, HD, FSB, power supply, MB, memory controller, network connections etc. Sharing all those resources will result in latency issues.

Imagine 4 sims hosted on the same rack. 40 avatars in each sim all gather at the center meeting point of the 4 sims, so they can each see and 'hear' eachother, then all start to walk across the sim borders in different directions. The amount of data that will have to be cached and transfered into protected memory areas, and across HD, to and from the asset server etc.... Theories are great... reality is something else.

Intel instead of AMD is a HUGE improvement.

For me, the quote from Kelly Linden read like: It is guaranteed, to the point where your sim will stay down when there's no free spot on class 5 hardware available. If you complain about that and want the sim to be up at any cost, they might change the class definition of the sim for you.

There was no analogy made there. That was a direct quote from Lee Linden....
/111/2f/66175/1.html#post690056

In the message he makes this statement...

"Before purchasing any multi-CPU systems, we tested them thoroughly. (They're multi-CPU, Wayfinder, and that is a dramatically difference performance situation than multi-core. If you can please correct this in any future posts, it'd be helpful.) The machines are well over twice as fast as a class2 machine. The CPUs are about 25% faster, and the total memory bandwidth is very, very fast (yes, over twice)."

The 4CPU statement was theirs not mine. All I added was the class 5 line, as the class 5 servers were the same as class 4 with various upgrades.

True, but that again applies to estates. Mainland is not going to get moved anywhere based on anyones request. It is entirely up to the Lindens where the sim is running. Again, as long as it is possible to move it from one class to another, there can be no absolute guarantee made as to what class server is running on.