I would like to replace the oldest drive in my array, and I'm wondering what the best approach would be. I'm a little hesitant to replace the drive and rebuild it from parity. Would I be better off by migrating the data off the drive and then removing it from the array. I could add the replacement drive later.

 

I guess this comes down to whether parity will need to be resynced once I remove the aging drive? I'm not clear on how unRAID handles removing a drive, so I don't know how it effects parity.

Hey-

 

I literally just did this.

 

So, is it the parity drive that will be replaced?  Remember that the parity drive has to be at least as large as the largest data drive you have.

 

In my case, I got 2 new 3 TB drives.  So first I got them on my server and ran preclear (3 passes each which took a total of about 80 hours per disk).  Then I powered down the server.  Pulled the parity drive.  Plugged in the new parity drive and powered up.  It recognized that the parity drive was gone.  I set the new disk to be my parity drive.  It resync'd the parity drive.  Once that was complete (with NO changes to the data on the array during this time), I let it run for a day or 2 to be sure all was good.

 

Then i powered it down, replaced the oldest disk, powered it back up.  It recognized that the old disk was gone and i set the new disk in its place.  It then rebuilt the data based on parity.  about 17 hours or so later (maybe longer) it was done.  all good.

Thanks for the reply!

 

I've already replaced my parity drive, and I'm actually repurposing my old parity drive to replace my oldest drive in the array. I believe what you described is the most common way to replace a drive. I'm just curious as to whether there are alternatives that may leave the array unprotected for a shorter amount of time. Although, 17 hours is really not that long.

 

It is good to hear that someone else has done this without issue!

No problem.  I guess it depends on a couple of things.  One of which is how large is the disk you are replacing?  If its a smaller disk, maybe it takes less time?  I'm not certain.  I replaced a 1.5 TB drive with a 3 TB drive.

 

I think when you add the disk, it will automatically start rebuilding the data.  I dont know that there is any way around that.  Maybe one of the smart guys out here can comment.

I would run a 'non-correcting' parity check before I replaced any drive.  If no errors are found, then replace the drive.  If there is an error, resolve that issue before doing anything else.

I assume you mean to let unRAID rebuild the "new" drive via parity?

 

Also, I want to repurpose this old drive as offline storage to backup some of the data on my server. Once it's been replaced in my array, I want to preclear it, then mount it, and copy data to it. That said, can I use the GUI to "remove" the old drive, then reassign my new drive to it's position.

 

I don't want there to be any conflict when the old drive reappears in my server to be precleared.

Yes, it will rebuild the new drive via parity.

 

You can preclear a drive with it NOT being a member of the array.  If it is replaced, it will not automagically be added to the array just because it is in the system.

 

It seems like you would be able to add another drive to your array to copy data to it.  But lets say you then remove it as an offline storage.  I THINK if you re add the disk to your array (lets say to replace a failed data disk) it will just be rebuilt from parity anyway.

 

If I were you, I would probably mount that drive in another machine (windows, etc) and just copy your backup data to it from the unraid server over the network.  That way you dont complicate things, AND you still have a backup of your important data.

 

Just my opinion though.  I'm sure some smarter people have opinions as well.

 

 

I prefer to keep my offsite backups in NTFS so that I can read them without unRAID. Instead of copying across the network to a windows machine I mount them outside the array with ntfs-3g.

That seems cool.  Does mounting the drive that way require a pro license if you have 3 drives in the array already?

That seems cool.  Does mounting the drive that way require a pro license if you have 3 drives in the array already?

 

I do not believe so. This is how I've been been making redundant backups of my critical data. It's much faster than copying across the network (at least for me). Here's a link for how to do it. It works for hard drives as well as USB drives the link describes.

 

http://lime-technology.com/wiki/index.php/Mounting_an_external_USB_drive_having_an_existing_NTFS_file_system_in_READ/WRITE_mode_to_transport_files_from/to_unRaid_server

 

emagsamurai's link shows the way...

That process has been turned into an unRAID plugin called, 'SNAP'.

It automates attaching and connecting a USB drive to your unRAID.

You can then use your PC or Midnight Commander, "MC", from the console to move files.

Oh yeah! I'd forgotten about that plugin. Good call!

 

I do this so rarely that I always have to Google it. I'll have to take a look at it again. For some reason I don't think I've used it in the past, but I can't remember why off the top of my head.