Kmod-fs-fscache

Folks
I am an great OpenWRT on 17.01.6 and have a SATA drive in EXT4 attached. I play video stored on it and was wondering if I could install cache file system. One option, not sure if available would be to do a ZFS with cache SSD. I wish I knew if kmod-fs-fscache is useful and how is that used...
Any pointers would be appreciated.
Thanks.
Anil Garg

First off, 17.X is no longer supported so you're on your own....

As for the actual question it doesn't make much sense as in general video files are quite large which makes them hard to cache due to memory constraints and you'll most likely be able to utilize ~500+mbit before hitting the limit of a spinning HDD even with multiple clients. Keep in mind that your clients will most likely not view the same clip so caching will be even harder. ZFS might "work" on < 2Gb of RAM but it's not recommended and it's a quite CPU intensive filesystem much like btrfs compared to lets say ext4 so unless you have a quite beefy x86 system you're probably better off running FreeNAS in the long run or something similar rather than trying to shoehorn such functionality in OpenWrt.

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Move to 18x is in my bucket list. Even though AppliedMicro APM82181 is 1GiG and it has 256MB ram, I can totally get your point about that the average consumer router is usually not designed to have heavy duty lifting....

But, we have only one client accessing the video file. Do you have any dope to share on kmod-fs-fscache ??

Could it serve any purpose. Is the configuration for this easy?

Thanks for your comments.

Anil

Don't get me wrong, all my FreeBSD and Debian boxes are running mirrored ZFS and I wish I could easily get the rest of my Linux systems to run on ZFS.

I think that you'll find that OpenWrt devices, in general, are ill suited for the load that ZFS puts on them, between compression and caching. Running ZFS on a 32-bit, x86 architecture with only 2 GB of RAM was possible, but there were major hoops to jump through for tuning so the box was stable.

I'm not sure what problem you're trying to solve with a single client. Video is typically only a couple mbps, so even a slow drive for a single stream should not have any starvation issues.

SSDs are dirt cheap these days -- around US$50 for a good-quality 250 GB drive (Corsair MX500 or Samsung 860 EVO, as examples) and not much more for a 500 GB (~US$70).

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Jeff: I too have a RAIDz3 on debian but it has 8GB Ram on 64 bit x86. And, I love zfs. Perhaps I can leave that machine on all the time....

But on another note, I have this curiosity bug..What in the world is fscache? and is that is a working Kmod?

Thanks.
Best Regards
Anil

https://www.kernel.org/doc/Documentation/filesystems/caching/fscache.txt

As to if it's working under OpenWrt, that is a wide-open question!

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I also think that caching is not going to improve your siruation.

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