Home Built NAS; this system replaces my QNAP TS-453 Pro-8G which was in use 24/7 between December 2014 and April 2021.

The intention is to use the NAS for up to 10 years before replacing the base hardware.

The SuperMicro SuperChassis 721TQ-250B2 is a Mini-ITX compact Mini-Tower which includes a Flex ATX 250W 80 PLUS Bronze-certified High-efficiency power supply.

While the case is intended for use with compatible SuperMicro mainboards and contains a proprietary front panel connector, it is possible to connect a 3rd party mainboard using the Supermicro CBL-0084L Frontpanel Split Cable adapter.

Clock Source
Using TrueNAS Scale the system was not keeping time very well as the system clock was drifting very fast compared to the hardware clock and losing minutes per day) and it turns out this behaviour was due to the "tsc" clock source. Changing the clock source to "hpet" works around the issue. This can be done manually by setting "hpet" as the clocksource in "/sys/devices/system/clocksource/clocksource0/current_clocksource" (the file "available_clocksource" in the same folder shows the supported clock sources).

To set the clock source at boot I tried adding "clocksource=hpet" to the kernel boot parameters variable "GRUB_CMDLINE_LINUX_DEFAULT" in "/etc/default/grub.d/truenas.cfg" and running "update-grub" once the file has been updated. This appears to work, but the "truenas.cfg" file appears to be reset to the default value at boot time.

As an alternative solution I added under Truenas Scale "System Settings", "Advanced", "Init/Shutdown" Scripts a "PREINIT" command "echo hpet > /sys/devices/system/clocksource/clocksource0/current_clocksource" to force the clock source override.

Cache Drive Replacement
In September 2021 the original Western Digital Black SN750 500GB NVMe SSD used as the storage pool's cache drive was found to be occasionally disconnecting from the storage pool. Online research suggests this may be related to an incompatibility with the B550i chipset. It was replaced with another Samsung 980 NVMe M.2 SSD 500GB drive and moved to an external enclosure.

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