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Replacing a failed/failing disk

So you've had a disk fail, or you know it's about to fail, and you need to replace it. And for whatever reason, the manual's instructions weren't clear enough. So, step by step, here's how to do it.

Note: The illustrations below describe the simple case of replacing a disk in a two-disk mirror. However, they'll work in any pool with sufficient redundancy or parity. This can be a mirror (of any width) or RAIDZn. There's absolutely no difference in the procedure.


Seriously, no part of replacing a failed disk involves clicking the Volume Manager button. Don't do it.

Log in to the FreeNAS web GUI, and click on the Storage button. On the page that comes up, click on your pool. You'll notice there are two entries with your pool name; click the first one (it's highlighted in the screen shot below).

Then, below the list, you'll see three buttons. The far-right one (the one that looks like a blank sheet of notebook paper) is the volume status button--if you hold your mouse over that button for a second, you'll see a tooltip pop up saying as much. Click that button.

In this screen, you'll see that the troubled disk is already offline. If it weren't, a third button marked "Offline" would appear below the list. Click on the troubled disk, and if you see a button that says "Offline", click it.

Shut down your server, remove the failed/failing disk, and replace it with a good, burned-in, tested disk. Power up the server.

Log back into the web GUI.


Just in case you forgot, do not click on the Volume Manager button.

Click the Storage button, select your pool, and click Volume Status, just as you did above.

Click on the entry for the OFFLINE disk on the Volume Status page. Then click the Replace button at the bottom.

In the window that pops up, select your new, replacement disk from the Member disk drop-down, then click the Replace Disk button. In a moment, the disk will be replaced, and resilvering will begin. The page will then look like this:

You can continue to use your server while resilvering is in progress, though performance may suffer.
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Great stuff, thanks!!
Thanks, that's a very clear and helpful documentation!
Great job. Styno makes a good point. One of the confusing things is, in various places, you see a drive referred to 3 different ways: name, serial number, and gptid number or whatever it is. The other part of this is figuring out which drive to offline and which one to select as its replacement.
I guess I should have taken the initiative and made something like this. I started my FreeNAS adventure using all second hand parts, including the hard drives. I have replaced every drive I ever installed in FreeNAS at least once.
Excellent job.
How about adding the extra steps/clicks on STOTAGE - VIEW DISKS to get to the serial number?
Have not had to replace a disk yet in FreeNAS. Figured I'd see what all the fuss was about. This made it brain dead simple, even a zombie could do it, (or a half asleep SysAdmin :-).
there was a need for this.
WTG on this! Could this be placed as a link in the Documentation/ Users Guide