Ok, so I have previously been running two 4TTB drives without a parity. Yeah, I know my data is unsafe. I have that data on an offsite backup and none of it is mission critical anyways. This, however, is changing now that I can afford to toss three 8TB drives in there. So, the plan is to get those drives precleared and add two of them to the array and have one as a parity, finally putting my money where my mouth is and having proper data integrity. Anyways, so I see a lot about rebuilding replacement parity disks and such and it seems to imply that the array is started while building the parity. This is building a new parity and I do need the array to be started and functional while I do the parity build, is this the case? I ask only because I use a pfSense VM and dockers on my server that require the array to be started to function even though all of their data is only on the cache disk, a cheap 120GB SSD I had lying around left over from my main PC after an upgrade.

 

I get the third 8TB drive in this Friday, my brother bought this drive as a donation to my server since he uses my Plex all the time. 😁👍 Pre-clearing is easy as heck while the array is functional since I just have to take the array down for literally 120ish seconds to add the drive to the array once that's done. I just haven't done a parity build before and no one outright states that the array is started and the data is accessible during the build process that I could find. No, I don't care if it's slower than molasses in a snowstorm going uphill as I won't be doing any of my months long file transfers till it's done building the parity so speed is not necessary, only the VMs and Dockers. 

 

Thanks in advance for setting my mind at ease.

The array is available when building or checking parity.   As you mention this might adversely affect performance if you try to read or write files on the main array while this is going on but it will still work.   The same applies if you ever have to rebuild a disk after a failure.

Beautiful, thanks! I just didn't want to set up my spare consumer router and not have my dockers up while it was working. I have a reverse proxy, remote access VM, a lot of things that don't use storage but DO need the array started anyways. This is perfect!