I'm wondering how quickly I will be back up and running. I know data wise, moving out and back about 8tb data will take at least a day. I'm wondering how long it will take to set up the parity drive and whether the system will be operational as it creates parity when the data is moved over 

you can use the storage while parity is being created, obviously sans any redundancy until complete.

 

Be aware that you'll probably top out around 50MB/s unless you enable turbo mode, even then you'll have a hard time getting twice that speed on average.  I copied over 12TB and it took 3 days over gigabit... keep in mind I never saw gigabit speed except in small bursts.  I also didn't know to enable turbo mode until part way through.  Cache won't help with this transfer, unless you have 8TB+ in cache

 

Getting used to the way things work will take a bit of time too, I'd suggest playing with a spare machine to get an idea of how things work to speed up the transition.

You can speed up the transfer to the array if you don't assign the parity until after you have finished transferring the data to the array.  However, there is still the file overhead if you transferring ten's of thousand of small files.  As a general rule, you will about double the transfer speed.  OF course, you won't have parity protection but you should still have the original data source at that point as a fallback.  

9 hours ago, andyd said:

I'm wondering how quickly I will be back up and running. I know data wise, moving out and back about 8tb data will take at least a day. I'm wondering how long it will take to set up the parity drive and whether the system will be operational as it creates parity when the data is moved over 

 

It depends on the level of operation you are after. Unless there are other issues, your server will still be operational (in the sense that you don't have to stop doing everything else) during parity build, regardless if your are transferring data at the same time or not. It's just slower or faster depending on what else you do at the same time.

• The faster way is, like Frank1940 mentioned, to set up Unraid array without parity, transfer the files over and then add parity disk and let parity build. The con is before the parity build is done, your Unraid array is not protected. However, the risk is mitigated since you presumably still have another copy of the data on the old server.
• The slower, safer way is to set up Unraid array with parity so your data is transferred while parity is built. Building parity + transferring simultaneously will be quite a bit slower (from experience roughly 25% typical disk speed). Also expect some latency due to high IO in the background.

 

In terms of how long to build parity, it's limited by your slowest disk. 8TB typically takes anything from 14-24 hours.

Edited June 24, 20197 yr by testdasi

Thanks guys. I don't really have a spare server to test this on. I thought about messing around in a VM though so maybe I'll do that.

 

I will have a backup of my data on external drives which I'll be transferring to / from so yeah should be less of an issue with data loss. If it's around 25% slower, I may go ahead with the slower safer option to avoid any issues

1 hour ago, andyd said:

If it's around 25% slower, I may go ahead with the slower safer option to avoid any issues

That 25% figure is probably true only if you are transferring very large files (like BluRay iso's).  If they are small files (like 1KB -100KB files), the file creation overhead and the drive head reposition times to write this information will really kill the transfer speeds.  Remember that with small files, you will have file overhead operations on both ends of the transfer as you have to locate where the file is on the source disk...

Yeah, I know. I will have small files to bring over for sure - mostly just metadata for media files