Questions about new mirror

Recently I decided to build a simple OMV setup to be used as a Rsync Server for my (Freenas) file server. The Nas I used for this, being a simple and not all that powerful Zyxel, had some trouble handling the Rsync jobs. Building the box and Installing OMV happened to be a simple job. But things got a bit strange (to me anyway) when I connected the 2 x 4 TB HDU's I retrieved from the Zyxel and added them to the OMV box. As I had them cleaned (I wanted a fresh start) I could see them at once listed in the RAID management tab. Setting up a mirror was easy. Now for the things that I found a bit odd:

• As soon as I saved the mirror a resyncing process was started. As I know better then to interrupt it somehow, I left it alone. It took over 12 hours to complete this before the mirror was marked "Clean". I don't understand what that is all about as the disks were clean and there was no data at all (or even a file system) to sync anyway. Is this normal behavior?
• Looking at the overview of the mirror I expected to see three devices. Two of them representing the physical devices and one of them representing the mirrored device. But there are 4 devices in the list and the presented capacities on three of the four devices make no sens to me. Only the capacity of the mirrored device makes sens as that is 3.64 TB which is about what I expected to see. I have made a screenprint of the overview of the raid (see attached file). The column labels are in Dutch, sorry for that, but I hope they speak for them self.

Just to be a bit more confident I have performed a long smart self test on both of the disks and no errors were reported. If somebody out there is able to explain what I see I would appreciate that very much. Most likely it is me being a noob, but I like to be sure before I trust this with my backups. Everything seems to work ok and it is my intention to add a filesystem to the raid as soon as I finish this submission.

Zitat von macom

Seems you have created partitions on the mirror.
The mirror should show up only as one device /dev/md127

Well, that is the strange part. The disk were cleaned with active@ partition manager and did not show any partition at all before I placed them in the OMV box. They showed unassigned space with the correct size for the disk. And I was under the impression that the raid tool in OMV only accepted and listed clean disks without partition. Still, I wil clean them up again (this time on the command line I think) and start all over.

OK. You live, you learn. I started with removing the raid. Not knowing if it was needed, but liking to do things systematically, I started with removing the just added file system. No problem. Then I got to the RAID tab to delete the RAID and what do you know: The RAID set looked completely normal. See attached screen print. I won't pretend I understand but accept it as it is. So let's make that filesystem again.

Zitat von macom

Maybe you also want to reconsider using RAID. You could also use two seperate HDD and use rsync to copy the data from one HDD to the other one. By this you can create snapshots and keep different versions of files.

The OMV box will only be a backup for my Freenas file server. Nothing more nothing less. Snapshots tasks on that box are running as we "speak". I will use rsync with push tasks from the Freenas box to the OMV box for backup purposes. The reason I use a mirror is simple. This box will be situated at another location (of site backup). And when (and not if) a disk fails, a raid buys me a fair change to replace it before the other one fails. And besides of that, at a certain point I see the need for more space anyway and replacing mirrored disks one at a time with bigger ones is more convenient to me then starting all over.

So as soon as I have enough trust in this thing and have run the initial jobs (otherwise it would take forever) it will be relocated. I am lucky that a friend of mine is good in all the internet/network stuff and he will be helpful with the configuration and the needed services etc.

Thanks for sharing your thoughts on this subject with me.