Hi y’all,

I am exploring TrueNAS and configuring some ZFS datasets. As ZFS provides with some parameters to fine-tune its setup to the type of data, I was thinking it would be good to take advantage of it. So I’m here with the simple task of choosing the appropriate “record size”.

Initially I thought, well this is simple, the dataset is meant to store videos, movies, tv shows for a jellyfin docker container, so in general large files and a record size of 1M sounds like a good idea (as suggested in Jim Salter’s cheatsheet).

Out of curiosity, I ran Wendell’s magic command from level1 tech to get a sense for the file size distribution:

find . -type f -print0 | xargs -0 ls -l | awk '{ n=int(log($5)/log(2)); if (n<10) { n=10; } size[n]++ } END { for (i in size) printf("%d %d\n", 2^i, size[i]) }' | sort -n | awk 'function human(x) { x[1]/=1024; if (x[1]>=1024) { x[2]++; human(x) } } { a[1]=$1; a[2]=0; human(a); printf("%3d%s: %6d\n", a[1],substr("kMGTEPYZ",a[2]+1,1),$2) }'

Turns out, that’s when I discovered it was not as simple. The directory is obviously filled with videos, but also tiny small files, for subtitiles, NFOs, and small illustration images, valuable for Jellyfin’s media organization.

That’s where I’m at. The way I see it, there are several options:

• 1. Let’s not overcomplicate it, just run with the default 64K ZFS dataset recordsize and roll with it. It won’t be such a big deal.
• 2. Let’s try to be clever about it, make 2 datasets, one with a recordsize of 4K for the small files and one with a recordsize of 1M for the videos, then select one as the “main” dataset and use symbolic links for each file to the other dataset such that all content is “visible” from within one file structure. I haven’t dug too much in how I would automate it, but might not play nicely with the *arr suite? Perhaps overly complicated…
• 3. Make all video files MKV files, embed the subtitles, rename the videos to make NFOs as unnecessary as possible for movies and tv shows (though this will still be useful for private videos, or YT downloads etc)
• 4. Other?

So what do you think? And also, how have your personally set it up? Would love to get some feedback, especially if you are also using ZFS and have a videos library with a dedicated dataset. Thanks!

Edit: Alright, so I found the following post by Jim Salter which goes through more detail regarding record size. It clarifies my misconception about recordsize not being the same as the block size, but also it can easily be changed at any time. It’s just the size of the chunks of data to be read. So I’ll be sticking to 1M recordsize and leave it at that despite having multiple smaller files, because the important will be to effectively stream the larger files. Thank you all!