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Comment by fsckboy | Hacker News Reader

good idea, but that's not his problem. he needs a media player that will sprint through to the end of the file when he first opens it. They don't do that cuz they figure they might be streaming from the net so why tax that part of the sytem.

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Thank you, yes this is my problem which most commenters here are missing.

I'm using Jellyfin server and Infuse on Apple TV, so I don't have a great way to force-slurp a file on first read, at least not without patching Jellyfin. And I'm not super eager to learn C#.

Even if I were streaming to mpv, most of my lan is only gigabit which is much less than what my storage array can put out.

VLC has all sorts of prefetch settings.

With ZFS that wouldn't necessarily help. I've been using ZFS at work for many years with mostly large files. Even if I repeatedly read the same file as fast as possible, ZFS will not cache the entire thing in memory (there's no shortage of RAM so that's not it). This is unlike most linux filesystems, which are usually pretty aggressive with caching.

Maybe there is some combination of settings that will get it to cache more aggressively; just saying that it's not a given that it will do so.

The ZFS ARC cache tries to keep a balance between most frequently and least recently used data. Also, by default, ZFS ARC only fills out to a maximum of about half the available RAM. You can change that at runtime (by writing the size in bytes to

  /sys/module/zfs/parameters/zfs_arc_max

or setting the module e.g. in

  /etc/modporbe.d/zfs.conf

to something like this

  options zfs zfs_arc_max=<size in bytes>

). But be careful, as the ZFS ARC does not play that nice with the OOM killer.

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