Server Admin Notes

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New Member
Jul 29, 2019
This is a list of known issues we have found with various mods specifically on larger servers with high populations and weaker servers with less power. Keep in mind, on well admined servers and smaller population servers most of these will never be an issue at all. Wen multiple mods and large packs are put on servers though sometimes a simple config change or small tweak can make a big difference.

This are not issues that are constant or bugs. They are issues that occur when you have a lot of mods interacting and large numbers of people using said mods. These are not bugs, which is why they are listed here as things server owners can tweak for performance as opposed to being listed in the bug threads.

These are the config options we change specifically for prevention of griefing/corruption.

CoFH Core - Pyrotheum Florbs are false -- grief prevention
Railcraft - Hidden Block is set to 0 -- prevents world corruption bugs
Project Red - Spreading Moss is false - lag issues
MFR - Syringes cannot inject players - grief prevention
Rotary Craft - Massive Mob spawn when harvesting spawners with a bedrock pick is off - lag concern for servers
Rotary Craft - RC Steel works for all mods requiring steel
Thaumcraft - Hard nodes turned off - if you generated with them on you need to turn on the regenerate nodes in the config or your world may become corrupted.
Thaumcraft - Chest animations with golem interaction this can cause a lot of client lag

MCPC+ causes many cross mod issues . We know why you want to use it. We even understand but if the bug can't be duplicated without MCPC+ its not a mod bug.

Many servers find they rapidly lose memory. The file below is one of the major culprits. It is generated every time vanilla detects a mineshaft and is added to. It lists the location of every block in the mineshaft. This quickly gets too large.

Mineshaft.dat in /world/data needs deleted daily. It grows too big and causes lag issues.

These mods have issues on many of the test servers. This may not be the specific mods fault. These are frequently caused by cross mod or MCPC+ interactions. This does not mean these mods are bad. Frequently it is just a case of too many mods interacting with each other. Mods are balanced to run by themselves unless they are addons. Once you start putting multiple mods together you start seeing issues.

Mods with known server issues:
  • Archimedes Ships: Large numbers of independently moving structures causes lag on servers
  • Project Red: Large numbers of logic gates can cause lag on the server
  • Quarries : Very hard on servers the more you have the worse it gets. This includes any mod modifying quarries.
  • Deep Dark from Extra Utilities: This plus chunkloaders lags servers, this + chunkloaders + ars magica is worse add in any mob mod and it gets even worse. Do not allow chunkloaders in this dimension.
  • IC2 : Large numbers of IC2 generators or machines with over-clockers can cause lag on servers
  • Open Blocks: Tanks. Making striped tanks where 1 large tank has multiple fluids is very very very hard on servers. Profilers will look like its the pipes of ducts causing the issue. But use a different tank type like RC or BC or TE and the fluid network performance will have a drastic increase.
  • Galacticraft: Same as any dimension mod this is very open to causing servers lag issues
  • ATG: World Generation can lag servers if generated too fast
  • Special Mobs: Mob spawns can cause server lag
  • Railcraft: Hidden blocks (turned off in our default configs) have cross mod issues due to a vanilla bug. Crashes and odd block behavior can occur.
  • Dimensional Doors and Mystcraft: Very open to over use on servers : Make it admin only.
  • Twilight Forest : Any dimensional mod can overload a server.
  • Teleporting Mods: Portal Gun, Mystcraft etc, rapid teleporting between a loaded chunk and an unloaded chunk can cause noticeable lag
  • Chunkloaders: Too many of these can be very laggy. Toggle the CCC config option to turn off chunkloaders if the owner is not on the server.
  • Thaumcraft - Taint spread due to flux can be used to trash a server via flux (disabled by default in our configs)
  • Deadly World: The arrow spawners especially can be very hard on servers
  • Railcraft and Buildcraft or any mod with moving/animated parts : Large numbers of moving/animated parts while more visually pleasing cause more render lag than static generators. This will affect client side more than server side. This is mostly because that's just how animated stuff works.
  • Thaumcraft: Taint and Dye trees biomes can cause corruption.
  • TrainCraft: Causes crashes and lag
  • Rotarycraft: Solar towers turn some blocks placed next to them into lava. This is intentional but players frequently call it a bug.
  • Ars Magica 2 : Cross mod issues with Chicken Chunkloaders - use a different chunkloader, either Railcrafts anchors or Dimensional Anchors.
  • Ars Magica 2: Cross mod issues with TE3 and Project Red, causing item ducts, conduits and redstone wire to stop working on chunk boundaries.
  • ArsMagica 2: Cross mod issues with TC4. Hecates destroy golems.
  • Mekanism: Large numbers of universal cables can be quite laggy. Use them only at machine connection points use a different type of cable/pipe/conduit for your main network.

Dimensions: Keep the number of these on your server limited. Whether its Twilight Forest, Mystcraft, AE, Thaumic TInker, Extra Utilities or Ars Magica, vanilla has a memory leak when dimensions are moved between. The more your users hop dimensions the more memory issues you will have. Your best bet is disabling unneeded dimensions and keeping Dimension creation as an admin only option.

Dupe Issues:
- If the railcraft hidden block is on all crafting tables that do the whole lay on the ground thing without a gui/block can be used to dupe items.

A good method of keeping up with memory issues for a server is simple : Set an automated restart every 3-4 hours. 30 secs of downtime every few hours is worth the performance upgrade you will probably see.

These mods have issues on many of the test servers. This may not be the specific mods fault. These are frequently caused by cross mod or MCPC+ interactions.

In many many many cases lag issues on servers are caused by incorrect jvm arguments.

Useful JVM arguments can be found here

Really and truly the correct jvm arguments can mean the difference between a laggy server and one that runs beautifully.
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New Member
Jul 29, 2019
Options in configs for performance:

Forestry: In the common.cfg

# set to false to disable particle fx on slower machines
# leaving this enabled will cycle the list of active players PER INGAME TICK to check for resupply via backpack. you want to set this to false on busy servers.

Applied Energistics:

graphics {

Mine Factory Reloaded:

# Set to false to disable the harvester's sound when a block is harvested.
B: PlaySounds=true

Setting the harvester sounds to false will stop the harvester from playing the sounds and displaying the particles when chopping trees and such. If you have a lot of large farms this can be a large performance increase.
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