Can someone explain to me what the issue is with leaving a Mac on 24x7? I am genuinely curious since as far as I can see it’s a complete non-issue for fixed Macs. I get that if your only computer in the house is a laptop that you actually use as a laptop - i.e. frequently take it out and about with you - then having DVR only work when your laptop is in the house on the home network would be an issue. But why would having a Mac that’s always in the house anyway power on 24x7 cause any issue?
The only possible explanation I can think of is power usage. But you’re actually going to use more power having another device (e.g. a NAS) on 24x7 to handle DVR in addition to the Mac that’s already there consuming power 24x7. The Mac will just wake up to record when it needs to then sleep again. I don’t see how adding another device consuming maybe 7-10W (http://www.alphr.com/wd/wd-my-cloud-2tb/32458/western-digital-my-cloud-2tb-review - seems to be at the lower end of typical NAS power consumption) 24x7 saves power compared to just using the Mac to do the job.
Even if you fully powered down the Mac every time when you weren’t actively using it rather than letting it sleep, you’d only be saving in the region of 6-12W (https://support.apple.com/en-au/HT201897) compared to just letting it sleep. And then replacing that with a NAS that uses 7-10W 24x7. Plus the environmental reports here (http://www.apple.com/environment/reports/) suggest e.g. for an iMac dating back to 2012, the power usage in sleep mode is much lower still - nearer 1.5W.
Am I missing something?