I will try to explain this to the best of my ability. I know true nas have a few features in place to create backups and snap shots
I also understand that true nas uses ZFS file system. My question is how do you recover lost data if your hard drives fail or you cannot access your Nas system
I’m trying to understand the most important parts of using true nas and one of them is recovering loss of data
Thanks for any info on this topic
if you are in such situation, is too late, you totally rely on your offsite backups.
Maybe klennet recovery tool can save something, but is not free.
If hard drives fails and you lose data, means that the pool is gone, instead if a drive fails but there is enough parity you don’t need to recover anything → only replace the failing disk.
When you say “cannot access your nas system” you mean situation like stealed-damaged by fire-water- ecc? If yes, same answer, offiste backup 
Neither snapshots alone can be usefull in those situations: they are on the same pool/machine, you need to replicate them on another location (here the offiste meaning). And for restore, the process is the same but source and target are reversed
In addition, make sure you have a safe (and even offsite) copy of your TrueNAS configuration. You can save a copy from the General Configuration screen. Make sure you include secrets (it’s a checkbox). That file contains all your TrueNAS configuration and credentials.
In general my friend @oxyde is correct and this is the typical way things happen. You need an offsite backup if you want to be protected.
As for actual recovery, it greatly depends on the failure. If the pool refuses to import, it may be possible to import the pool from several transactions before the failure, and that would normally be a Read-Only mount so you can pull whatever data remains off the machine. You will see a few of these type of problems in the forums but the vast majority are a total loss, or not worth the effort involved, unless you want to use a paid service to recover data, but it had better be some really important data for the cost. And even then the recovery is not guaranteed.
It is best to ensure you have sufficient redundancy and maintain your system. If you set it up and forget it, it will bite you in the rear later. Think of it this way, TrueNAS is corporate level NAS software and those corporations have people working all the time to monitor and fix small problems before they become big problems. You need to do something like this as well. It doesn’t mean you need to login every day to check on it, but you should make effort to read all the error messages it generates and act promptly to correct any issues.
Hopefully these two responses will answer your question. If not, be specific and we will do what we can to give you an honest answer.
Hopefully you’re not there yet.
This is something to avoid if you want to prevent yourself from being in a data recovery emergency situation.
Thank you guys so much I think you’ve answered most of my questions and concerns. I do try and backup my data on other machines. I also clone my main drives as well. I just want understand how and what true Nas can do in bad situation as far as recovery.
Thanks you so much
