I understand that when I write files to a DVD, they are not necessarily written directly to the DVD but cached somewhere, and when I unmount the DVD then that will force the files to be actually written to the DVD. But I *believe* that sometimes Linux will write from the cache to the DVD before I do the unmount itself.

My problem is that I am sometimes writing very large zip files to the DVD and when Linux does decide to commit them to the DVD from cache, it seems that the i/o takes over much of the system to the detrement of other running processes.

So I am trying to find out as much as I can about how Linux caches the files and what affects how much it will want to cache and what affects when it will decide to flush the files from cache to the DVD (apart from unmount). For example does the mechanism care about how many files there are vs how large the files are.

I am hoping to find out if there is a way to tweak some Linux settings or change how/what files I write soas to better meter out getting the files written to DVD without Linux having to suddenly commit so much resource to the i/o to make that happen.

Appreciate any links, insights, etc others can share.

FWIW, I am using the UDF filesystem when I mount the DVD.

do not know much, related is command sync, and the noatime command in fstab just maybe.
I suppose it is more of a kernel issue.
Also I suppose you are talking about RW dvd?

Jemery posted a tutorial on i/o bottlenecks.
Maybe you need strace, time, ps and other tools to really see what is going on.
What I am saying is, have you got proof it is a caching issue?
(maybe lack of memory, slow HD, but yeah , I guess I/O might be the issue)