Increase Speed Through SSD Cache or RAID?

Relixae · 9. März 2022

I'm been using OMV with Plex on my Raspberry Pi4 for a bit now and most 4k HDR movies seem to stream fine. I've recently added a few with higher bitrates that appear to me to be too high of a bitrate for my 5400rpm drive to keep up with. Plex is showing the average Bitrate at 106Mbps. I understand some scenes will use less and busier scenes will use more, I believe the HDD can't keep up because more static scenes are fine but busier scenes causes the stuttering.

Is there a way to get my files to cache to an SSD for faster read speeds? If not, would a RAID setup allow me to get around this if I can get data pulled from essentially 2 drives at once?

Zoki · 9. März 2022

You can not speed streaming up by a read cache in your scenario, as the stream read starts when you start streaming and you are reading fullspeed from the disk, so your cache would not fill up. There is no real lookahead.

You could go for raid0, but not with software raid, as OMV does not support raid on usb, but there are external cases, which support raid 0.

Maybe you can add a seperate ssd and put those files on there?

mi-hol · 10. März 2022

Zitat von Relixae

appear to me to be too high of a bitrate for my 5400rpm drive to keep up with

are you using 2.5" HDDs? As Zoki suggested switching to an external case with 3.5" HDDs would improve disc performance.

See benchmark results linked in my signature below

olduser · 10. März 2022

This is probably a Plex issue or a decoder issue. 100*60*90 = ~540 gigs for a 90 minute movie, 1/2 a terabyte for a movie...?

I'm not sure about your player or your system environment, but if you can wait ~3 seconds you can cache 300MB then use a named pipe, but that's dependent on the player. Mplayer derivatives can do it (SMPlayer, MPlayer, etc.). This isn't exactly straight forward though as it might be something like 2 named pipes, 1 to read from and another to update/replace the chunked file via cat or ffmpeg or something. If you're interested, look into how live streams start with inserting black frames then fade to the live stream (it's probably exactly the same). I did it years ago capturing cartoons with HUFFYUV to feed into FFMPEG, so researching "capturing" might also be useful.

Not sure now, but back when VideoLan was still VLC + VLS, VLS could cache up to 512 MB, that might still be an option.

Good Luck.

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