Best to to bakcup before restoring to newly created array

[NinthWave]

I actually have 3 disks (2 TB) in an Intel RST RAID 5 (don't blame me ).

I just got a 4rth disk and want to migrate to FreeNAS in a FreeNAS version of RAID10.

The 3 disks will be repurposed for that.

My question is:

What is the best way to copy/backup my data before unmounting my Intel RST array ?

I have a paid version of Acronis 2017, a paid version of Allway Sync and I could get myself used to Duplicati.

Thanks

 

[Etorix]

The best way is to have some other storage to copy your data to, and reuse all three disks at once in the ZFS stripe of mirrors.

If all you have are these four HDD, you have to take one drive out of the RAID5, make a stripe of two single drive vdevs with the new disk and the drive you've taken out, migrate the data from the degraded RAID5 to the non-redundant pool, delete the RAID and attach the two ex-RAID drives to the two vdev drives. If anything wrong occurs before the final resilver is complete, you lose all your data.

 

[NinthWave]

The best way is to have some other storage to copy your data to, and reuse all three disks at once in the ZFS stripe of mirrors.

If all you have are these four HDD, you have to take one drive out of the RAID5, make a stripe of two single drive vdevs with the new disk and the drive you've taken out, migrate the data from the degraded RAID5 to the non-redundant pool, delete the RAID and attach the two ex-RAID drives to the two vdev drives. If anything wrong occurs before the final resilver is complete, you lose all your data.

Thanks for your reply.

I should have mentionned that I do have a spare drive in an external enclosure for backup.

My question was more about limiting the fragmentation in the new NAS array.

But I just read that using conventional backup instead of sector-by-sector will remove fragmentation.

 

[Etorix]

Your pool will begin unfragmented, even after loading 2-3 TB in the transfer. Fragmentation develops over time and rewrites.