Backup of one NAS to another NAS + to expansion unit?

[tomiisek]

I have TS-873A with 8x 18TB and TS-653B with 6x empty 14TB.

Is it good idea to have RAID5 on source NAS TS-873A and back up the most important data to NAS TS-653B using also RAID5?

It means source RAID5 NAS will have 126TB and backup RAID5 NAS 70TB.

Is it possible to connect to source NAS also an expansion unit and backup remaining 56TB to JBOD expansion unit?

And another question - when JBOD expansion unit will have capacity 72TB and I will backup only 56TB to it, can I use remaining 16TB for another data?

[FSC830]

An expansion to main unit for backp purposes is always a bad idea!
If main unit is affected by any issue (malware, malfunction, theft, fie, ...) the expansion unit is affected too and may be useless.
JBOD is the worst thing to do, I would not rely to a JBOD device. if a disks fails, data at this disk is lost. Backup is useless.
As long, if your most important data does not exceed the backup NAS capacity all is fine. If you can live loosing the 56TB not important data, who cares... .

A backup to an external device (USB or another NAS) is the best thing you can do, Even better, if the external device at another place (disconnect USB devices after backup!).

Regards

[tomiisek]

Thanks!

I don't plan to backup 24/7, just to update backups occassionally and then switch off backup units for 4-6 weeks. Is it still bad idea to use expansion unit for those remaining 56TB when it won't be connected to main unit most of the time?

[FSC830]

If you setup the expansion in that way that it could be connected to another device, then not.
There are different modes for an expansion unit, one which allows to connect it to a pc or other NAS, the other runs only with the main unt.
But I never used such an expansion, I have just read this in several posts. So may be someone can jump in here.
Anyhow, JBOD is not the best idea.

Regards

[tomiisek]

I know that TR-004 can be connected to another device and that TR-004 can be used in RAID5 but I don't know if it works at the same time - to use TR-004 in RAID5 that can be connected to another device.

https://www.qnap.com/en/product/tr-004