Hi,
Im Using Truenas Core for about 4 years now. Currently on 4x4tb raidz2. But the space ist running out. I purchased 4x8tb and i want to move all data to the new Drives and then sell the old drives. I have a spare 8TB.
What would be best practice to so this? My Idea was to create a Backup on the spare 8TB Drive and then remove the old drives and add in the new Drives and restore from the spare Drive. I would be nice If the config would carry over to the new Pool.
Thank you!
Replace all the drives, one by one, with the larger drives. The pool will then expand.
In addition to what @Farout already wrote, you should burn-in those new drives before using them.
Burn-in means stress-testing and running for at least 2 weeks. If you are paranoid enough make that 3+ months. When moving to my current NAS in Q4 2020 I did the latter and still had several drives die during the first year.
Ok so in remove one 4tb Drive an add in a 8tb - my guess is the resilver Progress will start on the new drive. Isnt this more stressfull on the old drives than reading them once to a Backup and restore from there?
Thats sucks to hear… My current Drives we’re not burned in - guess i got lucky. I plan just to ready/wrote/verify every block once on the new drives.
If you have a spare port, add the new drive but do not remove the drive that is to be replaced.
Yes, but this is the easiest way to carry over the configuration 
The 4 drive replacement resilver is no more stressful than 4 x ZFS pool scrubs. (Which should be scheduled at least monthly, some do it weekly or every 2 weeks.)
Remember, in a resilver reads are from the other disks, just like a scrub would do. The main writes are on the new, replacement disk.
My opinion: Yes, replacing 1 4T drive with an 8T drive, letting it resolver, and doing the next drive will take a while (I did this on a 10-drive system and it took something like 2 weeks to do it all), and it will be stressful on the drives. And at some point one WANTS to stress-test the drives.
The question is should this be done “now” or “later”?
Do you have enough spare bays so that you can copy the 4x4T pool to a new 8x4T pool (if I remember your setup correctly)?
OK i thought i would have to replace the drives one by one to Trigger resilvering?!
Good to know, i scrub my Pool ever 2 Weeks. Guess the 4tbs are burned in now^^
That ist what i thought about. I would need a pcie2 SATA Adapter since i only have 6 Sata Ports.
That would leave the oldPool “untouched”. Can i expect the config to Work with newPool after i removed oldPool and renamed “newPool” to “oldPool”?
You can. Or you can use the “replace” function with the old drive still in place. ZFS will then offline the old drive once its done resilvering.
Ok thanks y’all!
For now i have once question left: At the moment i replicate my 8TB (6,5tb used) Pool to a external 8TB Drive. The new Config will have 16TB of usable space - can i still Backup to a smaller Drive If only for example 7,5tb are used?
Yes.
