So I stuffed up by buying a single 4TB HDD thinking I could add it in and have an extra 4TB.  I have not added any drives since I built the system so I forgot that I have to have a parity drive the same or larger than any other drive.

 

So now I need to push the new 4TB in as the parity drive, but I am not sure on how to do this.

 

Reading the Wiki, it says just put the drive in and it will format etc.  but what about pre-clear.  If I pre-celar the drive, it has no protection for 24+ hours (time to run pre-clear).

 

So what is the best way to replace the parity drive with a new drive while maintaining protection as long as possible.

 

Sorry for the newbie question

 

Mick

First, just to be sure ... you have to be running v5 to use drives > 2TB.    So if you happen to still be on v4.7, the first thing you need to do is upgrade to v5.

 

Now ... assuming you're on v5:

 

=>  Pre-clearing the drive has no impact on now long it takes to update the parity.  It IS a good idea to still do that, as it's a good test of the drive ... but doing a pre-clear on it won't have any impact on the system, so you can simply do that; and THEN upgrade your parity drive.    Note that a full pre-clear cycle on a 4TB drive will take ~ 40 hours or so.

 

=>  BEFORE you upgrade the drive, run a parity check and confirm the system is "perfect" -- i.e. no sync errors and no disk errors.    If not, get those corrected first; and re-run a parity check until everything's good.

 

=>  Now save a complete copy of your flash drive, so if anything goes awry you can restore that, restore the original parity drive; and recover any errors that may occur while writing the new drive.

 

=>  Now simply shut down;  swap the new parity drive for your old; and reboot.    The system will rebuild parity onto the new drive -- and you're done.    Note that you may have to Stop the array; unassign the old (missing) drive;  Start the array; then Stop it again, assign the new parity drive; and then Start it one last time to force the initial parity sync.

 

Thanks

 

Yes, its V5b12a

 

To do the pre-clear, can this be done in a spare slot and then removed and moved to the parity drive slot?

 

How do you recommend to make a full copy of the flash drive?  I'm running in a VM so would a snapshot be sufficient?

 

Also, the old parity drive, if I drop it into a new slot will the system format it or will it hiccup at seeing an old parity drive in a new position?

 

 

Thanks

 

Yes, its V5b12a

 

To do the pre-clear, can this be done in a spare slot and then removed and moved to the parity drive slot?

.

Do you mean physical or logical? The physical slot dose not matter. A logical slot is not required for pre-clear. The disk will appear in the disk assignment drop down but cannot be assigned in order for pre-clear to work.

 

How do you recommend to make a full copy of the flash drive?  I'm running in a VM so would a snapshot be sufficient?

If this makes a copy of the flash drive that you can access then it should be ok. You may only need certain files...  The flash is small just copy it to your desktop.

 

Also, the old parity drive, if I drop it into a new slot will the system format it or will it hiccup at seeing an old parity drive in a new position?

It will be cleared and then used. Save downtime with pre-clear.

Also, the old parity drive, if I drop it into a new slot will the system format it or will it hiccup at seeing an old parity drive in a new position?

 

As dgaschk noted, there's no problem simply assigning it as a new data drive; but you can save the time it takes to clear it by doing a pre-clear on this drive [AFTER you've successfully replace it, of course].

 

Since it's a well-used drive, you can use the -n option when you pre-clear it, and save the pre- and post- reads ... this will take about 1/4th the time of a full pre-clear cycle.    And after you've added it, run a parity check, which is effectively the same thing as a post read AND has the added benefit of checking the full array in the process.

 

Thanks for the info guys, all done now.

 

About 44 hours to pre-clear the 4TB drive.  Moved it over the parity with no issues.

 

One thing I noticed is that the system is capable of hot swapping.  I added the old parity drive while running and the system detected it so I could run a pre-clear on it without a reboot.  Once finished it was successfully added to the system.

 

The drive bays are hot swap (Norco 24 drive case)

 

Znelbok, the vm snapshot does not save your flash drive. So before doing anything got you your unraid gui, navigate to the flash folder and copy all of it somewhere safe and accesible even if unraid is down.

The best is to wait until preclear is done , shut down unraid, remove flash and copy it on other computer.

 

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