JonathanM

This. For the home user, it makes much more sense to either build a second box with spare or castoff parts that can hold multiple drives, or simply keep external drives laying around. The prices for spinning rust capacity are dropping quickly enough that it's cheaper to keep 2X the hard drive capacity than it is to use tape. Tape quit being economical for the home user around the time Imation Travan TR-4 was the current tape format. The tape drives are just too expensive and finicky. Now, I suppose if you were to source relatively recent tape drives from the same type of market all those e2650's came from, and paid similar 10% of new retail, it might get interesting. Still a BUNCH of work getting and keeping it running.

Instead of using the web GUI backup, try stopping and powering down, put USB1 into your 10 desktop, copy the config folder to the 10 desktop somewhere, remove the USB1 key file from that copy, eject USB1, insert USB2, copy the config folder to USB2, making sure the key file for USB2 is put back in the config folder.

That is the root of the issue for Unraid's disk use as well. Since any single file must entirely fit on a single volume, even though the folders can span multiple volumes, you must guess correctly when setting the minimum free space or you will fill a volume and generate an error. Unraid is not well suited for HUGE files. It works much better with backup software that has the capability to generate multiple discrete files for a single backup, which most backup software can be configured to do. Directly recording unbounded video files to disk is not friendly at all, for multiple reasons. Better to use an Unassigned Device as the target, and then manage the results from there. If you truly need 100's of TB of single volume space, Unraid can be wrestled into compliance, but you will lose much of what makes Unraid work so well otherwise. There are rumblings and rumours that things may change on that front, possibly Soon™. Maybe later this year.

Yes, it rebuilds the entire drive partition with the file system as is. Some people misunderstand and think you can recover files from parity, but that's not how it works. It uses all the remaining data drives plus the parity disk(s) to recreate the missing drive. When you replace a drive, if it's smaller than your parity drive, you can rebuild to a drive the same size as your smallest parity drive and Unraid will automatically expand the partition to use the new space while it rebuilds. Very similar to traditional RAID levels as far as drive replacement and rebuilds, with the added advantage of each data drive being a readable file system instead of a bunch of stripes. Disadvantage that read speeds are limited to single drive speed, and write speeds are less than half that because of latency penalties updating 2 drives. With modern drives touching 200MB/s, it's not THAT big of an issue for most folks, and you can change the parity write method to spin up all drives and increase the write speed. The upsides of Unraid for most home use cases far outweigh the speed penalties.

Unless you got the 4TB drives for free or a substantial discount, it would be better to just use 2 more 8TB for data. Same capacity, but lower power consumption and easier future capacity expansion, plus lower risk. Also, with so few drives, you would be better off using only 1 parity disk and keeping the other as a ready replacement for a possible drive failure, not permanently connected. It sounds like you already may have a solid backup strategy. Keep in mind that parity disks are not backup, they are for high availability so the array stays running with your files still accessible when a drive fails. Running a mail server requires a lot of cooperation from your ISP, they need to be ok with updating the ptr records for your IP so reverse dns lookups return your domain instead of theirs. https://www.itworld.com/article/2833006/how-to-setup-reverse-dns-and-ptr-records.html

Step by step describe how you accomplished this.

Was the server properly powered down before you made the copy of the files?

If there are 3TB drives in the parity array, one of them MUST be the parity, which means the 2TB assigned to parity in your first screenshot is really a data drive, not parity. Unraid will not allow a smaller drive to be assigned as parity. Go to Tools, New Config, preserve none, then go back to the Main tab and assign all the drives as data drives, DO NOT POPULATE either of the 2 parity slots, they must say unassigned.

You will lose single thread performance and gain a bunch of cores and RAM. If you don't plan to change the role of the server and add a bunch of other duties, I don't see the point in changing.

Yes. Unraid will partition automatically, and apply whichever format type (XFS or BTRFS) that you have set for that cache slot. XFS is only available if the number of cache slots available is set to exactly 1.

You can use the cache disk slot to format to XFS as long as you set the cache slots to display only 1 slot. That way it doesn't disturb the parity array and still sets up the drive correctly. If you currently are using a cache drive just disable the VM and Docker services in settings while you do the unassign current cache, assign temp drive, format, unassign, reassign all current cache drives.

https://www.monoprice.com/product?p_id=34898

Started in maintenance mode.

This is very strange, as I have never run into an instance in 30+ years of working with OS's that write to the console not working with a standard 25x80 character display. Something has got to be very broken with that video BIOS. I can understand if it was the GUI boot option that was giving all the problems, but the 25x80 text only display should work regardless of drivers. Do other live distro's or console utilities work completely ok? If so, which ones work?

I just use SMB/CIFS and connect the shares I want that way. Mapping should work also, but that's not how I set mine up. I just have read only access to shares, any user file writes I keep in the nextcloud database file structure. I don't use nextcloud to add data to my shares. No experience with dropbox.

https://www.techrepublic.com/article/how-to-add-external-storage-on-your-nextcloud-server/

No. You can't "shrink" an already occupied data slot. Parity doesn't have any concept of data, or how full or empty a drive happens to be. If you want a better evaluation of what your best options are, I'd advise attaching the diagnostics zip file to your next post in this thread.

Set Unraid to shutdown after 5 minutes (300 seconds) on battery, set the VM to shutdown after 4 minutes (TIMEOUT 240) on battery. You want your system completely shut down as soon as it is clear the power is not coming back, typically if the power is out more than 1 minute, it's going to be out WAY longer than your UPS can handle. The last thing you want is to drain the batteries, you want to reserve as much battery as possible.

The license is tied to the USB stick, not the motherboard.

That only means that the physical drive that was assigned to parity at the time the backup was taken was found. Doesn't mean that drive was your parity drive currently. However... if that drive is the only 2TB drive and all the others are 1TB, it must be parity. What sizes are all your drives that were in the array when the USB died?

I wouldn't leave it in the array. Theoretically possible it could be revived, but failing the long smart test is a bad sign.

Maybe since you ran preclear in the enclosure, so it was on a totally different controller, sometimes those USB SATA drive controllers remap the drive geometry somewhat.

Tools, diagnostics, attach the zip file to your next post in this thread.

Sounds like a solid plan. Not everyone has issues with BTRFS, but it's not tolerant of memory issues or power cuts, which is why I mentioned server stability.

I'm asking about the physical connections to the drives. How many discrete sets of cable runs from the PSU to how many drives. Any splitters? etc.