Multi-folder install performance...Myth?

[dbick]

Back in the early days of Everquest, I 3 boxed using a program called WinEQ (created by Lax). Many times during those years the question was asked if installing EQ on multiple drives/folders would increase performance. The general consensus back then was no. In fact, the question was raised so many times that Lax added it to the WinEQ2 FAQ:

"Q: Should I use the same folder for each session of my game, or separate folders?
Short answer: Same folder
Long answer: It is a common myth that game performance can be increased by using mulitple folders, possibly even on separate
hard drives. The thinking goes that using separate copies of the files will allow them to be used independently and hopefully faster than
trying to use the same files. However, this is not the case. A relatively simple concept in computer science says that hard drive
accesses are slow, and memory accesses are fast -- about 10 milliseconds for hard drive access, and under 100 nanoseconds for
memory access (as low as about 5ns depending on if the memory is stored on the CPU or if it is system RAM, etc), a ratio of 10 to 10,000,000.
That's a pretty big difference. The point of explaining this is modern computer systems employ several "cache" systems to reduce the amount of
file accesses as well as file access times by reusing unchanged data directly from memory, or by predicting the next data to be retrieved
(for an easy to understand example, if you read the first half of a file, you can be expected to also read the second half). By using a
separate folder, these cache systems cannot recognize that the data being read is actually the same. This means that instead of 10,000,010
nanoseconds for loading time for two sessions, it will probably be 20,000,000 nanoseconds because the entire data must be read twice. In
terms of loading time, you have absolutely nothing to lose by using a single folder on a single hard drive, and can reasonably expect it to
be faster than using multiple folders, regardless of whether it is on another physical hard drive. Note that it may be possible in some cases
to see performance increases by using a separate hard drive, but the hard drives MUST be on a separate IDE channel, or they are competing
for the same resources anyway (or use SATA, etc), and it is still unlikely that this will show improvement over a single folder."

Source: http://www.lavishsoft.com/wiki/index.php/WinEQ2:FAQ


This explanation seemed to make sense back then and I have considered it general computing knowledge until now. Nowadays I am reading all over this forum about multi-folder installs/symlinking and it got me wondering. I know that things change considerably in the computing world and that EQ was a long time ago but I still wonder, has the advances in hardware and operating systems made this advice obsolete?

[Coltimar]

All I can say for a fact is that when I ran 5 Wow's from 1 folder I had frame latency, in game freezes and (for some reason) ms latency. I moved to 5 symlinked folders and all of that evaporated, completely.

[Shaitan256]

I'm just using 2 Folders 2 accs started on my System HD and 3 accs on my 2nd HD, better Performance then running from 5 Folders. Oo? Don't know why, but it works best for me. and I need only 2 Folders, Mybe I spread it to my 3rd hard drive, but then I'm afraid of getting heat Problems. Beacause that would be 2 Running wow in my Case .

(My system HD is an external HDD with eSATA2 )

[Sam DeathWalker]

I do what lax says.

Most of what people do here is the symlink, and not seperate folders without symlink. But it might be time for fresh eyes to go over the situation as that is some very old post, but I been following it for years.

Also some use seperate folders cause they have different classes and set ups.

What he says is true, unless more modern cachs do things different.....

[Tight]

I totally agree with Coltimar.
Symlinking took away all my problems more or less..

[Bovidae]

I use multple folders for saved variables. There are many settings that are better if not cross contaminated with the other instances.

That said, I have found better load times in all installations being symlinked to one data folder. This is in agreement with the OP and is very VERY common practice around here.

[Zzyzxx71]

I run out of 2 folders - one for the main driver, mainly due to the fact that his addons are so indepth, and a second folder, from which I run all the slaves.

i run all of this off of a 64gb SSD. no issues, fast zone times.

[Souca]

You will get the best performance out of multiple folders that symlink back to a master folder for some of their contents. The reason you shouldn't run multiple instances in the same folder is that you will get contention for some files. Wow has cache files as well as log files that it reads and/or writes from/to. If these files are shared, you could end up with some file locking issues. Data files, however, are only read from and by symlinking these you gain the benefit of the both the filesystem cache and potentially some hard drive caching.

In theory, you should aim to have your read only files together, and you read/write files seperate.

I was going to write more and go into more detail, but work distracted me.

- Souca -

[heffner]

I started with four separate folders. It worked, but load times were insane. Once I symlinked the folders loading (i.e., using the boat etc.) was instant. Loading still takes time when I log in and when I enter instances. I don't know if I could make this any better. My slave box (4 toons) isn't much different in load times relative to my main toon that's on a separate computer.

[Sam DeathWalker]

Ya I could never understand the advantage of symlinking. I run wow from the same folder on all 5 instances of my guys per computer.

I seriously doubt there is a performace advantage symlinking vs. running from a single wow folder. Both would be better then running from say 5 seperate wow folders.

All are right about the global settings/character settings being a mess but I have worked around that by complicated automated changeing names inside of the files in the wtf folder.

But that lets me change macros on all 25 shaman at one time, I would guess with serperate wtf folders per characer you have to change macros in game serperatly for each character.