Forum Discussion

Aspirant

Dec 08, 2020

Turning 2disc JBOD volume into RAID

I currently have 1 JBOD volume including 2 x 3TB disks. Is it possible to change it into RAID without destroying it (e.g. by adding disk). If not is it possible: May I duplicate everything into new v...

kemot

Aspirant

Dec 09, 2020

Thanks Sandshark for answer, but it is not addressing my situation. I try to be more clear.

Now i have:

1 volume including 2 disks. It's listed in GUI as JBOD. But i think more acurate will be to show it as RAID 0.

I would like to:

have 1 volume including 3 disks but protected with redundancy like RAID 2; preferably without destroying current volume.

My question:

What's the best way to do it? May I just add aditional 3TB disk, and will be able to choose proper RAID solution?

StephenB

Guru - Experienced User

Dec 09, 2020

kemot wrote:

1 volume including 2 disks. It's listed in GUI as JBOD. But i think more acurate will be to show it as RAID 0.

RAID-0 and JBOD are in fact different. If you started with a one-disk volume and added a second disk, then you have JBOD. If you started with two disks, you could have created a RAID-0 volume that spanned both disks.

The difference:

With JBOD, the space on the two disks is simply concatenated together.
WIth RAID-0, the disks are actually striped.

To make this more concrete - when you copy a file to a two-disk RAID-0 volume, the file's data blocks are spread across both disks.

If you copy a file to a two-disk JBOD volume, the file's data blocks are only on one disk. Note the metadata might be on the other disk.

kemot wrote:

I would like to:

have 1 volume including 3 disks but protected with redundancy like RAID 2; preferably without destroying current volume.

You must mean RAID-5 here. The NAS doesn't do RAID-2 (AFAIK, no NAS supports it).

If your data fit on one 3 TB volume, then you could

create a new volume with the new 3 TB drive
create temporary shares on the new volume, and copy your data to them.
uninstall any apps
destroy the old volume
select one of the original disks, and add it to the new volume for redundancy (RAID-1).
select the second original disk, and you should be able to add it for capacity (converting the volume to RAID-5).
reinstall any apps.
rename the shares to the original names.

But your data doesn't fit on a 3 TB volume, so you can't do what you want non-destructively. The direct way to do it is to back up your data, do a factory reset with all disks in place, rebuild the NAS and restore the data.

I guess you could also back up about half your data, delete it from the NAS, and then use the above procedure to non-destructively handle the rest of it.

kemot
Aspirant
Dec 09, 2020
Thanks StephenB for answer.

Does unistalling apps and installing again retein its configuration?

For example I have resilio sync app with several shered folder throught resilio. I would like not to restore it manually.

If it is not possible by this method, you explain in other post method of moving apps by ssh. Would it be possible in this case?

I can reduce total data storage to 3TB.
- StephenB
  Guru - Experienced User
  Dec 09, 2020
  kemot wrote:
  
  Does unistalling apps and installing again retein its configuration?
  
  No. The problem here is that the apps are stored on your data volume, so anything that destroys that volume also deletes the apps. Since there are some app-related settings on the OS partition, it is best to delete/reinstall, and not depend on the ReadyNAS application to clean everything up when the volume is deleted.
  
  kemot wrote:
  
  If it is not possible by this method, you explain in other post method of moving apps by ssh. Would it be possible in this case?
  
  I can reduce total data storage to 3TB.
  
  Sandshark has tested this with ssh, not me. Hopefully he will chime in. I don't think he's tested ssh with a jbod volume that spans two disks though.
  
  Note you need to get below about 90% of 3 TB - that is about 2.4 TiB as reported in whe NAS web UI. That's why I suggested backing up half your data.
  - Sandshark
    Sensei - Experienced User
    Dec 09, 2020
    My adventure in moving apps to another volume can be found here: How-to-save-your-apps-when-destroying-your-main-volume-OS6 . Note that my experiment assumed that all configuration is either in the apps folder or on the OS partition, which should be the case but I can't verify for Resilio.
    
    Multiple drives in a single JBOD are a configuration I've not played with.
    
    I suspect (perhaps StephenB can verify) that it is two single-drive RAID1 MDADM volumes (which sounds odd, but is possible) with a BRTFS file system spanning them both. If it is, then it's possible via SSH to shrink the BTRFS volume down to a single drive once some of the data has been moved off. But I'd have to test it to give the exact steps, and don't currently have the time. It would be quite an undertaking, and I wonder if saving your app configuration is really worth jumping through all the hoops. Here are my adventures in shrinking a volume to remove a drive: Reducing-RAID-size-removing-drives-WITHOUT-DATA-LOSS-is-possible , but it is for a different configuration than yours.