I tried to find a more applicable community to post this to but didn’t find anything.

I recently set up a NAS/server on a Raspberry Pi 5 running Raspberry Pi OS (see my last post) and since then I’ve got everything installed into a 3D printed enclosure and I’ve got RAID set up (ZFS RAIDz1). Prior to setting up RAID, I could transfer files to/from the NAS at around 200MB/s, but now that RAID is seemingly working things are transferring at around 28-30 MB/s. I did a couple searches and found someone suggesting to disable sync ($ sudo zfs set sync=disabled zfspool). I tried that and it doesn’t seem to have had any effect. Any suggestions are welcome but keep in mind that I barely know what I’m doing.

Edit: When I look at the SATA hat, the LEDs indicate that the drives are being written to for less than half a second and then there’s a break of about 4 seconds where there’s no writing going on.

  • ramenshaman@lemmy.worldOPEnglish
    3·
    5 days ago

    I don’t know what ARC is and my searches so far haven’t helped. The CPU usage is pretty low, on htop is rarely passes 10%.

    Edit: I asked chatGPT what it means, this seems like exactly the setting I was hoping to find. I’ll check it out and post an update.

    Edit2: I changed the ARC size to 8GB and it definitely seems to have gotten slower.

    • Lemmchen@feddit.orgEnglish
      2·
      5 days ago

      Do you have the 8GB version of the Pi 5? You shouldn’t set the ARC to 8GB then. Usually it about half of the available system RAM. I’d probably set it lower if there’s only 8GB available in total.

    • Creat@discuss.tchncs.deEnglish
      2·
      5 days ago

      ARC is the in-memory cache used by ZFS. If it’s completely off the effect can be dramatic. Under no circumstances should a larger cache cause anything to get slower, ever. Even the raspi didn’t have memory that is that slow that this is a reasonable outcome. By default on most distros, ARC size is capped to 50% of physical system memory. Keep in mind it is a cache: if something else needs needs the RAM, it will be released.

      As a concrete example: I was recently working on a server where a maintenance task that should take like 12hrs or so at the worst somehow took 2 weeks (!) and still wasn’t finished. That was ARC being disabled.