I've read that there is 1 (or 2) parity drives, but does this mean that these drives always spin up with everything you do? Wouldn't that shorten its lifespan significantly compared to a SHR configuration?
SHR is mdadm RAID. It means:
- you can lose more data than the drives you've lost
- you MUST to spin up ALL drives for mostly everything
- you need all the disks as well in some kind of service recovery situation (like for example you still have all the disks fine but your box died, you need all 8 or whatever number of disks to be connected to do anything, can't just take one disk and use the data from there)
If you WANT to spin all drives all the time with unraid of course you CAN do that, but otherwise you CAN spin up only the one from where you read (or the one you write to + the parity). That is of course an advantage, you can do as you wish.