ZekerPixels Posted January 2 Share Posted January 2 (edited) Hello everyone, I have some questions which come up and cant seem to find a clear answere, all regarding, parity, swapping, adding and removing drives. I will describe it in steps what I'm doing or planning, to have a story to the questions. To no surprise, I need more space. I have been looking out for good hdd prices and haven't found anything of interest over the past year or so. I have price alerts set, but prices in my region price don't seem to drop. Anyways, I got one drive to swap in the parity and temporary use it as a additional drive, too increase storage for now. 0. Current Configuration I use dual parity and while exchange disks I want to hold the parity valid. Original Configuration; Parity1; 8TB Parity2; 8TB Disk1; 4TB Disk2; 4TB Disk3; 8TB Disk4; 8TB Disk5; 8TB Disk6; 8TB 1. Swapping parity I got a new drive which is the now my biggest drive, so it has to become the parity drive. (precleared the disk and zerod) This is easy to do by unassigning the old drive and assigning the new drive, where it begins to rebuild parity1 and parity2 stay valid. So, I assign a zeroed disk as parity1, which is basically a XOR, right? Well, during the rebuild it passes the 4TB point, where those disks spin down and it continues to rebuilt. It passes the 8TB point and those disks spin down. But now it is still continues writing to rebuild the parity for hours, but why? Because we already know the 8TB left of the 16TB drive is all zeros, because we have done the pre-read, zero and post-read. There are no other disks, so its zero. and XOR 0 and 0, stays zero. New Configuration 1; Parity1; 16TB Parity2; 8TB Disk1; 4TB Disk2; 4TB Disk3; 8TB Disk4; 8TB Disk5; 8TB Disk6; 8TB 2. Adding a disk As I mentioned, I need space and now have a 8TB drive left. I will also preclear/zero this drive and add it to the array as Disk7. I have not done this before and most information is regarding a single parity drive. But I assume a assigning a additional disk to the array, which is zerod, parity1 based on XOR stays valid. I'm not sure about parity2, it is Reed-Solomon based but idk does it need to rebuild? New Configuration 2; Parity1; 16TB Parity2; 8TB Disk1; 4TB Disk2; 4TB Disk3; 8TB Disk4; 8TB Disk5; 8TB Disk6; 8TB Disk7; 8TB 3. Future As I have now added a 16TB drive, I have the intention to eventually add/swap in more big drives. As well as removing Disk7 from the array, to a total of 8 array drives. I want to remove Disk7 again, because it would be the only drive which isn't mounted on dampers and to reduce noise and power usage from the additional drive. As described before swapping a disk in, is assigning the new drive an let it rebuild. But now removing Disk7 and I'm specifically looking to do this without breaking parity1, because I think parity2 will always need a rebuild. So I need to remove all the data off to the other disks and then zero the drive so parity with XOR stays valid. Has anyone actually done this https://docs.unraid.net/unraid-os/manual/storage-management/#alternative-method Possible Future Configuration; Parity1; 16TB Parity2; 16TB Disk1; 16TB Disk2; 16TB Disk3; 8TB Disk4; 8TB Disk5; 8TB Disk6; 8TB Edited January 2 by ZekerPixels Quote Link to comment
itimpi Posted January 2 Share Posted January 2 1. The parity build does not check whether a disk has been precleared so it always does the full size of the parity drive. 2. I would avoid this if possible as removing a drive to shrink the array can be problematic. Quote Link to comment
Kilrah Posted January 2 Share Posted January 2 5 hours ago, ZekerPixels said: Has anyone actually done this Done it twice without issues. Some have had speed problems even if I can't understand why. Quote Link to comment
ZekerPixels Posted January 4 Author Share Posted January 4 I have just swapped the parity drive, done rebuilding and check. But I needed more space, the original plan was to add a Disk7. I have decided to not to a Disk7, just to be safe of potential issues with removing Disk7 at a later point. So, with the recent addition of the 16TB drive, I can get 4TB of additional storage on the array using the drive I have now. I just have to expedite the purchase of another drive to exchange. Plan for now adding 4TB to the array; Parity1; 16TB Parity2; 8TB Disk1; 4TB Disk2; 8TB Disk3; 8TB Disk4; 8TB Disk5; 8TB Disk6; 8TB Quote Link to comment
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