My array is 16x3TB plus 3TB parity.  Two of my 3 TB drives are giving SMART errors.  Drive 16 is unable to complete a SMART self-test.

 

Drive 13

197	Current pending sector	0x0032	200	200	000	Old age	Always	Never	3

 

Drive 16

197	Current pending sector	0x0032	200	200	000	Old age	Always	Never	4
198	Offline uncorrectable	0x0030	200	200	000	Old age	Offline	Never	1

 

These drives are 4-5 years old so I thought it best to replace them with new 6 TB drives.  I've read the documentation on replacing drives in the array.  Since I am replacing a 3TB drive with a 6TB drive, I need a 6 TB parity drive.  The documentation describes a "swap-disable" procedure where you replace the old parity with the new larger drive, and use the old parity drive in place of the failed drive.  Ok, no problem.

 

My question is, when do I pre-clear the disks?  I'd like to stress the new drives during the pre-clear so I can RMA them if there are any problems, before I put them in the array.  Do I run pre-clear on the new parity drive?  How about the old parity drive that I am moving?

 

Are there any other tricks to swapping the parity drive?

 

Thanks!

First thing you should is run an extended SMART test on disk13, if both 13 and 16 have bad sectors you won’t be able to complete the rebuild part of the parity swap without at best corrupting some files on the rebuilt disk.

Ok.  Looks like the SMART test ran ok earlier today, but now is not completing.  Report attached.

 

Should I try to move as much as I can off the failing drive before rebuilding parity?

WDC_WD30EZRS-00J99B0_WD-WCAWZ0176723-20160316-1741.txt

The best option, if you have the available space, is to copy everything you can to another disk, it also depends if you can get the files you won't be able to copy due to read error from another source.

 

If you can't get the damaged files from another source and don't have backups, you can still do the rebuild then use a file compare utility between the rebuilt and the old disk, chances are that different files will be damaged, so with some time and patience you could get all files.

Ok.  Thanks, I will start moving stuff off disk13 and disk16.  I have room in the array.  I will check but I don't think anything on those drives is irreplacable.  Once I empty out the disks, then I should replace each, one at a time, right?  Rebuilding parity each time.  Would I do a pre-clear on the new drives before the swap?

You can rebuild one at at time, if the disks are empty, the read errors that may happen when rebuilding the first disk won't matter, or, also if they are empty, you can replace both disks at the same time, do a new config and start a parity sync. The first option takes more time but it's somewhat safer in case another disks has issues.

 

Both these options don't need cleared disks but you shroud always preclear before using any new disk in the array to make sure it's reliable, or use an alternative disk testing util.