well i was wondering,
i always tested with sv_pure on 0
now when i set it to 1 i get the error: Re_Loadworldmap: maps/…bsp not found
is this because its is not in a pk3 ?
nevere really thought of it before what this exactly does, so just asking for better understanding why i would use certain settings 
understanding what i exactly am doing would be nice after making 4 maps and running 3 servers 
as far as i know this sv_pure setting turns on and off some checks by the server. mainly to ensure consistency between client mapinformation (.bsp) and server mapinformation.
so yea. it could be that you didnt pack your map, because i think thats one of the precondition for stuff like checksum.
but im not sure. but whatelse would it be then. at least this was the explanation i always gave to myself
as far as i can remember i heard the argument “when it is set to 1, it will only look for centent within the pk3, and when its set to 0 it will look outside the pk3 also”
so when i test my maps, it makes sense it only works when set to 0, cuz no pk3 is made at the point.
but i never really have know the exact reason and i am wondering of this above statement is true. if i remember correct, i have also tested maps when it was on 1, and no pk3 was made.
but now i am working on a new map, and i am starting to have second doubts on the above statement, and even be a little affrait when its done and the pk3 is made, i mag get errors i than can not fix anymore thats why i rather understand it correct now when its not yet too late 
best explanation from google that i can find is:
To solve this error, go to the console and type /sv_pure 0.
Now, try loading the map again. You only get this error if at all when the map is not in a .pk3 so when you release your map, players will not experience this error.
guess there is not much of a better explanation to it
You almost got it. sv_pure compares client’s pk3 to server’s pk3 and if something is wrong kicks the player. When sv_pure is set to 0 all client’s pk3 and outside pk3 are loaded.
mmm but in that case, when i test my map on my local machine, sv_pure 1 or 0 does not make a difference.
Mappers view:
0 - You don’t need to pack it up to test your map locally. And you don’t need to update pk3 every second! If a file can be found packed and unpacked, packed is used.
1 - You can test if your pk3 is fine because the stuff outside pk3’s is not loaded.
Servers view:
0 - I don’t give a *… do whatever you want and use whatever you want.
1 - The pk3 you have must be exactly the same server has or you won’t be able to play.
Players view:
0 - You can replace files in the pk3’s. The clients pk3 is not checked if it matches the servers one (you can replace playerskins with hot pink etc.)… Also you can use your own skin/soundmod pk3’s.
1 - Oh boy this rocks, everybody is on the same line!
I’ll check this post in the morning. Am dead tired.
pure server= you have my files, or GTFO unpure server= HERE USE ANY FILES YOU WANT TEEHEE
(off topic) Unpure servers are pretty unfair because you can make cham mods.