What's happening during a maintenance?

Lebkuchen

I am asking, because sometimes it makes performance worse on Playstation EU.

Luke_Flamesword

The feed server hamsters but sometimes they eat too much, so there are lags for some time.

Lebkuchen

That makes sense. Now i understand. Thank you. Explains why it sometimes gets better after a while. I guess the Gray Host hamster ate something wrong and got very ill during the maintenance on August 3, 2022. He has been very sick for almost 4 months. Yesterday the Blackreach hamster was ill too, i hope he did not catch the same thing and they both get better soon.

Haenk

I assume there is a login peak after the servers are back, which hammers the servers.
Maybe some cache files will be created from scratch after a reboot, but that's just a wild speculation.

Sir_Gentleman777

Lebkuchen wrote: »

I am asking, because sometimes it makes performance worse on Playstation EU.

As i am not working for ZOS i can only take a few educated guesses. I assume that ZOS uses some form of memory based databases such as Times10 or similar. These databases reside in memory but after maintenance they need to be pulled into memory from the storage devices. This is sort of a caching explained from 10,000 feet to keep it simple. To read all required records first from a storage device takes time. After maintenance there are thousands of players connecting and all records need to be pulled from the storage at the same time. This is the reson why the system also puts you sometimes in a queue, to spread the load and that it takes some time until the system runs smoothly. As ESO is a massive game there are millions of records in the databases. Just imagine how many thousand records there are for just a single player. There is your bank, your inventory, your houses, your gear load out, skills, CP, costumes, location, buffs and debuffs and much more. You can also notice this when you login the time required will be longer than usual.

Then during maintenance all instances will be stopped and restarted. Each instance spawns multiple child processes, which will have a limited lifetime. Imagine there is a parent process that spawns instances for each dungeon. You enter this instance and finish it. This instance might be ended here and a new one is respawned for the next group, or it might be re-used for the next group to safe performance on the spawning of new processes. Now after maintenance there will be only a handful of instances spawned and new ones need to be added. That is where you feel that the performance is worse than before maintenance. From an IT perspective spawning new processes is expensive in regards to computing time.

When maintenance starts they will also probably clear the transaction logs and wait that everything is written to the storage before backing up the database. This does not affect the performance directly that you experience, but explains why maintenance takes quite a bit of time. Another reason will be that the systems need to be shut down in a specific order to not cause inconsistencies. Depending on what servers they are using, what OS etc. it might take some time until a server is switched off. And then you can only restart the servers in a specific order again and you need to wait until the provious server is confirmed running before starting the next. Again this costs substantial time. A server start might take an hour until all services are fully running and only then you can start the next set. Especially database servers can take their time.

So no, running a system like ESO needs, is not as easy as turning on your PC and the performance will be worse after a restart, but increase gradually. It is like starting and driving a car. First the starter needs to turn until the motor starts, then the engine needs to warm up before you can really floor it and drive 200mph.