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Hi guys I'm little noob in Linux and i have 2 8TB hdds. someone told me to JBOD them but how can I do that in ubuntu 20.04? Right now they are ext4 what should I do to make them JBOD?

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    Are you sure you want to do this? What is the use case? A single directory with 16TB of content? Or will there be a finer degree of allocation? The reason I ask is because setting up disks in a JBOD or LVM (to have what looks like a single, large volume) is not easily "undone". For this reason, it's important to know ahead of time what the ultimate goals are.
    – matigo
    Jul 8, 2021 at 13:25
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    Are your disks in a RAID configuration acting as 1 right now, or are they separate drives? All JBOD means is "Just a Bunch Of Disks" usually in the same storage enclosure. Depending on the controller, some systems do JBOD as Single RAID 0 drives, while others just have the drives formatted as separate drives. Can you please specify what is your ultimate goal here? Thank you!
    – Terrance
    Jul 8, 2021 at 13:29

1 Answer 1

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If you simply want to join two disks into a single virtual disk without making any changes to those disks why not look at FUSE?

https://github.com/libfuse/libfuse

I use it to access a copy of my home NAS file system when I'm at my second home in France. I'm not worried about resilience as I always have my NAS original (and a full backup on another offline NAS as it happens). The total file system size is 7TB, so I have split it across two 4TB disks in France.

The two disks are mounted in an external USB drive box and appear individually on my local server. I combine the two drives using FUSE so they also appear as one file system, just as they do at home.

This is the command in my fstab file:

mhddfs /media/1.42.6-7308,/media/1.42.6-73081 /media/NAS_copy -o ro,nonempty,allow_other,dev,suid

1.42.6-7308 and 1.42.6-73081 are the two individual 4TB USB drives and NAS_copy is the combined file system.

Note that I've made it read-only as it's just a local copy, but you don't have to! I use rsync to update the file system periodically. I also have a crontab job that "touches" the usb drives every 5 minutes to stop them going to sleep as that can break the FUSE file system:

*/5 * * * * /bin/touch /media/1.42.6-7308 &>/dev/null
*/5 * * * * /bin/touch /media/1.42.6-73081 &>/dev/null

The advantage of FUSE over JBOD is that if one disk dies, I simply rewrite the contents to another drive. The second drive doesn't need to be touched since the disks are entirely independent. The disadvantage is that it is lower performance than JBOD but, frankly, that's irrelevant to me in this situation.

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