This is something I’ve been requesting for over 10 years. I don’t think (as a guess) that there is the appropriate type of memory in a Sonos device to store that data across a power cycle.
The flip side is that it is also one of the ways I can tell when there has been a firmware update for the speakers, in which Sonos reboots the system, too…while I don't lose the playlist, it does reset the playlist to the first ‘song’. Interestingly, it does reset the ‘random’ nature of the playlist, so after that first ‘song’, I do get new randomization of the playlist.
@Airgetlam is correct. The non-volatile memory (flash memory) used by Sonos has limited write cycles; that is, there is a limited number of writes before the material starts to break down. Once a sector has deteriorated, it is marked as unusable, causing an ever decreasing storage capacity, and eventually breaking down entirely. There are typically around 100,000 write/erase cycles until the circuit begins to deteriorate. For this reason, the writes are kept to a minimum (system settings, service information, new units, etc.). If the system was writing out the queue to flash memory every time the queue is added to, deleted from, or otherwise edited it would reach the limit of the memory very quickly.
It is also very slow to write to, which could cause a performance hit. But this is secondary to the write/erase limit.
Sounds logical and that I do understand totally. Thanks for that detailed explanation. Then, I will try to configure a workaround like “Check the queue every 5 Minutes and in case it’s empty add at the default radio station”. I don’t know yet how to determine the empty queue (I’m using Home Assistant with Node Red addon), but in my experinence this should be possible in some way.
It isn’t something I frequently care about, although living where I do now, there are more frequent power outages. Nor is it all that taxing for me, as long as when Sonos updates the firmware, I can skip the first song.
For me, it’s an extremely minor concern. Sonos has much bigger fish to fry, and as @jgatie suggests, ‘fixing’ it likely won’t happen, for the reasons he outlined.
Something to keep in mind about the flash memory is that new Sonos have a vastly improved number of write cycles over older Sonos so what might be possible for new gear would shortly trash older gear. You can see some of this on the topics discussing older Connects on S2 versus reverting to S1.
Writing only on power-fail or reboot sounds like an option but it is risky as if the power is gone before the writes are done you have a mess. That is why most SSD drives have a limited power storage capability, it lets them finish the current write cycle and not corrupt the device. Maybe not so much your data but that is far easier to restore.
