MegerFS/OMV peculiar/slow behaviour

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    • MegerFS/OMV peculiar/slow behaviour

      I''ve been reading and digesting the manuals and other threads i found in google but nothing quite covers the issue i have. Or i have missed something, so here i'm.

      I have a pool of 4x2tb WD reds with MergerFS, 250gb WD black for OS, Rig: AMD A10-7850K, asus board Gb onboard, 8gb Ram.
      The server is wired to a Asus AC68U with cat6 and my gaming/workstation has wireless AC68 PCIe card. I get steady 75MB/s with this.
      (I know wired should get me a another 30MB/s but i'm not in a rush when doing bulk transfers)

      I had this issue last year also but it went away after i did a fresh install of OMV4.0 from messed up OMV3 and rebuild the pool from a 8Tb iron wolf back up in December.
      The thing is that it came back a week into running the rig with the new setup. I almost lost my bongers when i saw this again. since that i've been on the issue on and off and thought to give the forums a shot as summer holidays are coming and i can have more time for fixing this, if needed.

      The Behaviour. Protocol Smb/Cifs, Windows 10 to OMV/mergerFs

      When i transfer data to the pool i only get data bursts of about 2gb at max link speed (50-75MBs Wlan, 90-110 wired) then the CPU util drops to idle and transfer rate drops to zero. During transfer CPU in OMV is around 20%.
      The transfer pause can stay like that for minute or so and then the transfer continues at max link speed for another ~2gBs then to zero again. Sometimes i get more than 2gb bursts but at speeds about 30mB/s
      but usually not past 5gb burst. There is no difference which MergerFs settings i use (I've tried direct_ios on/off etc. one disk full first then the next etc, least space, most space...) or how full/empty the drives are and there is no other difference than speed if i use cat6 wire to the AC68U from workstation.

      This is driving me nuts. I don't mind having only 60MBs, i can leave things running when i leave for work but damn i can't handle this kind of weird funkyness from my hardware. :S

      I don't think its HW issue with OMV/merger as PLEX does a fine thing transcoding files on the go without an separate transcode/cache SSD. Also the rebuild of the pool and data recovery from the 8tb drive worked just fine. Also Snapraid and other back ups run fine internally on the rig.

      Anything i can/should do or shall i just suck it up? NFS any better etc...I have saturated my brain on this matter and if nothing else then i could use a different opinion for a change, or if nothing else then some one to say "sorry, nothing you can do!" I need closure! :D

    • Hi,

      Thanks you for the tips!

      I'll have a read about the samba tune up.

      Had a read test from the pool and i get 95MBs continuous with 10gb file with the wireless to my workstation, and yes only when writing to the pool has this weird up and down bouncing. Only one windows machine actively writing to the pool when i start the transfer, no automatic syncs etc.

      I have the 8TB backup drive shared in the network with smb/cifs and did a write test to it and i get steady 45MBs the whole 10GB file. So some thing with samba, Merger and/or windows is messing the pool writes?

      I do not have another *nix box in the network. I could swap drive to one of my laptops and install something to test if needed.

      I'll report back when i've had a change reading the samba tune threads.