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How long To Prepare New Drives (SOLVED)


jgourd

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I added 4 2TB drives to an existing array that had 4 2TB drives. When I went to start the array it started to clear the 4 new drives and it has been hours since the web GUI has responded. Is this normal? The array appears to still be offline as i can't access it.

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If you did not preclear the drives first, it is busy writing zeros to both drives.

You might be sitting there for 8 hours. it depends on your hardware... just let it do its thing and not think about it and try back tonight or tomorrow.

 

I assume you can see activity on the drives while you are waiting..

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(Edit: Johnm posted while I was typing, but what he says is correct.) 

 

This is why many people use the "preclear" script.  Your array will be off-line while unRAID prepares the drives to be added to the array.  It cannot do this instantly since as far as unRAID is concerned they contain random data, and so they must be cleared first to avoid invalidating parity.  If you are initialising four drives at once, you may find that the clearing could take some hours depending on the capabilities of your hardware.  By some hours I mean typically 8 hours up to maybe 20 or more.

 

If you had run the preclear script instead, this would have two benefits.  Firstly it runs without taking your array off-line so that the down-time when you are actually adding the drives (after the preclear process has completed) is literally just the minute or so that you spend adding them to the array in the web interface.  Secondly, it exercises the drives by writing and reading every block of data and also by rapidly causing the drive to seek to different areas from time to time.  This allows the drives to deal with any defects that they may find and to reallocate sectors as needed, and it also helps to weed out any drives that may suffer from premature failure.

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You could...  But, you have to stop the array, remove the drives just added from the drive allocation.  Then restart the array.  Then run the preclear script for each of the new drives.

 

However, since you have already signalled to unRAID that the new drives are added, you may have to jump through a few more hoops.  Specifically you may need to clear out all the drive allocations, and then reapply the setting for the data and parity drives and then restart the array.  There is a procedure known as "trust my parity" which will tell unRAID to proceed and allow things to come up as though nothing had happened.  You'd then be advised to do a parity check (just in case).  [i think this is correct - I don't go down that path very often.]

 

Personally, unless you are confident, or unless you have a real need to get the array back on line quickly, I would sit tight and let unRAID complete the process that you have already started.  It's the easiest and safest option at this point.

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