Start off with one disk, add second disk later and create mirrored / RAID 1 array, is this possible?

Zitat von Streglof

Is this possible in OMV without having to wipe all data on the first HDD and having to create a completely new RAID 1 array from scratch?

No, it is not possible.

Most people here would not suggest to use RAID1. Instead use your first drive as primary drive and then using rsync to sync the data from the primary drive to the second drive which would become your backup drive. Even better is to use rsnapshot instead of rsync. That way you even have a versioned backup. Thus you can go back in time and restore previous versions of the drive.

If you add off-site backup you have a pretty solid backup strategy.

My thoughts about... RAID

https://blog.storagecraft.com/5-reasons-raid-not-backup/

Zitat von Streglof

I assume the backup drive would be accessible through its own drive path?

Yes

Zitat von Streglof

If I were to replace the primary drive, I take it I would have to rebuild the primary drive from the backup drive, correct? Would I still be able to access my files during this process?

Yes, but on the backup drive. You have to create shared folders to the relevant folders on the backup drive and add them to the service you are using to access your data.

The backup thing.

Zitat von Streglof

Is a backup more secure than a mirrored disk? how so?

A mirror is not a backup, it's a mirror.

You have File A that is super important.. you or someone else accidentally deletes File A... File A is then deleted on both drives. That's not a backup, it is a mirror

A Backup, File A gets deleted, and a copy is stored at another location/on another drive, thus making it easy to restore.

That's as simple as I can make it.

Did you read the article I linked?

If you saved a file with a modification you don't like it is instantly saved on the mirror.

If you delete a file by accident it is instantly gone on the mirror.

If you share gets encrypted by malware it is instantly encrypted on your mirror.

Nothing of this happens if you have a versioned backup like if you use rsnapshot.

If you use rsync it will still happen, but only after the next run of rsync.

Zitat von Streglof

Since in RAID 1 there is never the necessity redirect anything when a drive fails?

Your argument here is about availability, yes if a drive fails within that mirror then the mirror is still 'usable' but your still looking at performance degradation particularly when the mirror is being rebuilt and leaving the raid to rebuild without accessing it is a better option.

If you want to use a Raid setup at least ensure you have a backup!!