Practical experiences from every day IT

  • Grafana replaces datasources from older imported dashboards with the default datasource

    … potentially rewriting the dashboard json code in sometimes unexpected and unwanted ways.

    When importing some old dashboard that used “null” as datasource, newer instances of Grafana do replace this with the default datasource. In my case, where datasources such as Graphite and Prometheus are mixed, this can be very annoying when importing a dashboard that was made for Prometheus.

    One solution can be to bulk-change the occurrences of

    "datasource": null

    with sed:

    sed -i 's/"datasource": null/"datasource": {"type": "prometheus", "uid": "${DS_PROMETHEUS}"}/g' dashboard.json

    This declares the datasource to be a variable datasource to be chosen by a custom annotation.

    It also prevents Grafana from removing correct Prometheus queries for panels, which it does, if it things that the datasource is a Graphite datasource.

  • Kingston SUV500 with Dell PERC H730

    Both the PERC H730 and the Kingston SUV500 are really old hardware. Not only that, they also served two completely different markets: Enterprise versus Consumer. But that should not be a reason for the problem I describe next: There is some strange incompatibility running the Kingston SUV500 with a DELL PERC RAID-Controller (both in RAID- and HBA-mode).

    I recently had acquired some old server hardware to solve the recent, sometimes unpredictable, pricing changes for virtual and dedicated servers. Since the R330’s have plenty of free slots, I have had someone print me a couple of DELL 2,5 inch caddys and off we went to install the machines.

    After the initial installation on the SUV500 as a OS-disk, I started to encounter strange anomalies:

    • getting stuck at “Booting from Harddisk C:”
    • getting stuck at PERC controller initialization “FW initializing 33%”
    • slow performance after controller cache was used

    Forth and back I tried to play with the cache settings as well as HBA-mode, with no success. Updating the SUV500’s firmware on a Windows box that I luckily had around, with no success. Then I researched the problem a little and found that I am not the only one with problems in that constellation.

    And despite the forum members in some forums spreading useless, even stupid misinformation about the interoperability of enterprise- and consumer-hardware, the core truth stays the same: Somewhere in the firmware of at least one of the components there is something wrong. The complexity of reproducing and analyzing the problem deeper might make it impossible or at least very unfeasible for me.

    I went and installed another 2,5 inch SSD for the OS, some Samsung PM8xx model with 256GB. All went fine.

  • Does the MikroTik USB port work with an BELKIN F5D8053 v6?

    Unfortunately, as of May 2026 and RouterOS 7.23, no.

    The BELKIN F5D8053 v6 is basically a Realtek RTL8191SU/RTL8192SU, which currently does not seem to be supported to act as a Wifi interface for RouterOS on ARM32.

  • External USB to ethernet adapter on MikroTik USB port – does that work?

    Short: Yes, it does. But likely only with specific network chips.

    In my case, I tested with a small USB-C docking adapter, which I connected to my hAP ax S via USB-A to USB-C adapter as shown in the picture below. The chip is a Realtek RTL8153, which was immediately recognized by RouterOS and added as “ether6” interface to my interface list. (The hAP ax S without USB attachments features 5 ethernet ports called ether1-5 and 1 SFP port called “sfp1”.)

    MikroTik as of right now does not feature a compatibility list of attachable network chipsets. They have a page called “Peripherals” which poses as a compatibility list for LTE modems, SFP modules and U.2 disks. I will inquire with MikroTik support if they see sense in adding a section for ethernet adapters.

  • USB hub on MikroTik hAP ax S and other MikroTik devices to connect multiple storage or broadband devices?

    Short: Yes, works. I tested a Dell D3100 docking station with a built-in active USB hub in conjuction with the USB port of the hAP ax S. The following things worked find out of the box:

    • connecting 1-2 broadband LTE dongles and access them at the same time
    • connecting 1-2 storage devices and access the files on them
    • connecting all 4 named above at the same time

    All cases worked flawlessly in both 7.20.x and the latest stable 7.22.x of MikroTik RouterOS.

    Important to note is, that the docking station of course is actively powered. Given the small max power output of the USB port, this is the only way to run multiple LTE dongles AND storage devices in parallel.

    Something that did not work yet is the docking stations internal Ethernet chip, even though it advertises itself as CDC_NCM but specifies no further chip it is based on. Given the non-existing amount of documentation about running additional ethernet ports via USB on MikroTik-devices, I assume the chances to be very small that this would work, anyway.

  • ffmpeg for recording from v4l2

    Every now and then some old VHS pops up after cleaning old storages, shelfes, workshops. And I am by far not a professional VHS digitizing service, but some VHS’s are really worth preserving to me, so I have a cheap VHS player and a Hauppauge USB-Live2 analogue USB capture device.

    A very simple way to capture the video and store it, would be:

    ffmpeg -f v4l2 -framerate 25 -i /dev/video0 -t 03:10:00 -f alsa -i plughw:2,0 -c:v libx264 -vf format=yuv420p -preset ultrafast -crf 23 -c:a aac -b:a 192k output2.mp4

    One could ofc adjust some parameters. In my case this was running on old hardware, where everything more CPU-bound than libx264 with the “ultrafast” preset would congest the CPU too much, leading to frame drops.

    The point here was also never to store in archive quality, for that I would need another VHS playback device with a TBC (Time Base Corrector) to decrease the horizontal jitter in the VHS, anyway. They are expensive. Or I would have to enter the whole new world of vhs-decode. Maybe one day.

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