Why do updates take forever to patch?

[McJiggy]

Seriously no other game takes forever to download and patch updates like Euro Truck Simulator 2 does, what's up with that?

[Ryu]

Not having this issue, myself. But it's a Steam thing, not a game thing. Steam sends you the files and updates the game. Latest update took less than 2 minutes for me; download and patch combined.

[Peno11]

I used to have the same problem with both ETS2 and ATS on my old computer. However, ever since I upgraded to a new computer with M.2 SSD, on which I installed both games (before that, I had both games installed on HDD, because my old 250 GB SATA SSD did not have space to install games). I can't tell if it was that or something else on my old PC, but something on that PC definitely slowed ETS2 and ATS updates significantly down. Not sure if that is your problem or if it's something else. Just stating my experiences.

[evilspoons]

Euro Truck Simulator 2 is mostly a bunch of gigantic files (base.scs is 7.5 GB, etc). Steam patches files by applying the change to the file and rewriting it to the disk.

This means that a single gigantic 8 GB file with 4 MB of changes incurs a complete 8 GB rewrite, so it's restricted by the time it takes to read out 8 GB and then write 8 GB. A typical hard drive is in the range of 100 MB/s, so best-case you're talking 2.5 - 3 minutes to modify that single file.

On an expensive M.2 SSD, you can do 6000-8000 MB/s so that same process takes 3 seconds so you don't notice it.

Some other game made up of hundreds of tiny little files only needs to update those individual tiny files that are being patched, say, four 1 MB files, and you're done in less than a second even on a hard drive.

This is a common issue with Steam with games that are patched frequently and have gigantic-ass data files. I switched Path of Exile off Steam and to its own launcher for exactly the same reason.

It might be helpful if the game dev sliced the huge main files up into 1 GB chunks or something.

[The Pitts]

It would indeed help, because some updates only touch a single file (the manifest, that contains the version number) in each .scs, but ask yourself whether you'd rather they spent time on reworking an existing fundamental part of their technology that works perfectly well but causes an issue for a decreasing percentage of their user base or they spent it on other improvements to the underlying engine? Sadly the Steam hardware survey doesn't seem to track SSD vs. HD but you would have to suspect that HD users are an ever dwindling percentage of the user base.

[room217au]

Originally posted by evilspoons:

Some other game made up of hundreds of tiny little files only needs to update those individual tiny files that are being patched, say, four 1 MB files, and you're done in less than a second even on a hard drive.

Further to your post..
def.scs = 29,492 files | 1779 directories | Size on disk: 56.5Mb
base.scs = 145,426 files | 3,681 directories | Size on disk: 20.2Gb
dlc_balkan_e.scs = 9,841 files | 508 directories | Size on disk: 885Mb
The only time the entire archive is downloaded in one chunk is on a new install.
Because everyone doesn't have the same DLC purchases and so on, the updater seeks through archives and updates necessary files, but perhaps not all of them.
I included a map expansion archive as an indication of what's possibly required to be updated. Add Going East, etc and we're talking an enormous number of decisions even before the transfer and writing.
Considering the above, any update to ETS2 is reasonably quick, tbh.

[edit]
It took longer to inflate the three archives I mention, than than it did to update to 1.44 open beta at the time of release.