[conspire] backup/restore or "clone" lxc container on RAID?

[Ivan Sergio Borgonovo]

I've a 4 bays server with a RAID array with a pair of disks for the host 
os and another RAID array for a single guest.

This is the second md device:
UUID=b2ff855c-ffc6-458a-9abe-90d3be006b65 /var/lib/lxc/caronte    ext4 
defaults,noatime 0        2

I've 2 newer, larger HD, a spare HD large enough to hold the content of 
the lxc container and one single drive SATA/USB3 enclosure.

I would like to replace the old HD of the second RAID with newer and 
larger ones.

I've understood there are several way to do it each one with its 
subtleties that I've not completely understood.

I was even planning to buy something like

https://www.amazon.it/dp/B06XRK93R9/?coliid=I3GS886IOKZ1GR&colid=YSMDPI7IC2HA&psc=1&ref_=lv_ov_lig_dp_it

as an investment to make future backups a bit more comfortable.
I'd like to buy something that has the least amount of software that is 
not debian. So semi-proprietary NAS are not an option and anything that 
can be turned into a NAS with Debian seems way too expensive.

Reducing downtime would be a good thing but I prefer something that if 
anything goes wrong or half wrong won't make me stuck half way.
It should be easily reversible or better... easy.

It's hard to understand if those enclosure can be used as Linux soft 
RAID otherwise I'd feel comfortable in...

1) create a soft RAID on the enclosure
2) rsync it live with the container
3) when most of the content has been copied, stop the container
4) rsync the rest
5) swap the HDs
6) recreate the RAID
7) mount it in fstab

Then supposed this could be an optimal way, I've other 2 questions:
- probably I don't have to rsync the /dev subtree but I'd prefer not to 
go by trial and error before I guess the right rsync command line
- is it worth to buy an esata enclosure or it won't make that much 
difference to buy a USB3 enclosure, considering that I don't have esata 
ports on the server, but I have them on other network connected devices?
Is it hard to chose wisely? I've had some trouble with an old usb3 
chipset and an enclosure that seems to work perfectly on a newer PC.


Any preferable alternative?

thanks


-- 
Ivan Sergio Borgonovo
https://www.webthatworks.it https://www.borgonovo.net