During the initial parity sync I understand that my data is not protected if I write to the array.

 

However, if the initial sync finishes, will it then sync parity for the data I wrote while it was initially syncing?  That is to say, will it get me caught up and make my data (that was written during the initial sync) safe?

 

There is no answer to this in the manual or on the website; simply that it is unsafe during the initial sync.

 

Thanks!

During the initial parity sync I understand that my data is not protected if I write to the array.

 

During the initial sync all array data is not protected because if a disk fails before it finishes you won't be able to rebuild it, but any data written to the array updates parity in real time, it's just not recommended to do huge writes during a parity sync because it will slow down both operations considerably.

But will that initial data I wrote during the sync get parity data written for it afterwards?

But will that initial data I wrote during the sync get parity data written for it afterwards?

No, it will be written at the same time. That is what real-time means, and that is why it will slow down both the initial sync and the data writing.

Just to further clarify this since you seem to have a fundamental misconception. Any write to any array data disk will update the parity disk at the same time. There is never any catching up to do. This has the result of making writes to the parity array somewhat slower than the speed of a single disk write.

Then how is it "unprotected" during the initial sync?

I just reread.  I understand.  Thanks for your help!

Then how is it "unprotected" during the initial sync?

Any data you write during the initial parity sync will have parity when the data is written, but all of the data already on your disks from before you started building parity don't have parity yet.

Yeah, I never considered having data on the disks before building the array.  In my case, I'm building a new array with clean disks.

 

As long as anything I write gets protected as I write it (i.e. parity data built in real time) then I'm good.

 

Thanks again.  (Phones are not the best way to read forum posts.)

Yeah, I never considered having data on the disks before building the array.  In my case, I'm building a new array with clean disks.

 

As long as anything I write gets protected as I write it (i.e. parity data built in real time) then I'm good.

 

Thanks again.  (Phones are not the best way to read forum posts.)

Even if the disks didn't have any files on them, if they were formatted before parity was added, then the empty filesystem on the formatted disks have "data" that affect parity. Only clear (all zero) disks don't affect parity. Newly formatted disks are disks that have filesystem data on them that represents an empty top level folder.

 

Conversely, some people have tried to replace a disk with data on it to rebuild it, and somehow thought they needed to format the new disk before they could use it as a replacement. Format means "write an empty filesystem to this disk". That is what it has always meant in every operating system you have ever used. unRAID treats this write just like any other, by updating parity so that it agrees that the disk has an empty filesystem on it. Obviously not what you want when trying to rebuild a disk that had files on it.