Hi all,

 

I wish to remove a disk from array to use as back up disk.  The disk in Question is disk3.  It doesn't contain any data.  I've excess capacity and disk3 is doing nothing except consuming energy. Can I do the following without jeopardizing the whole array:

 

1) Stop array

2) Unassign disk3

3) Shut down to pull the correct disk

4) Power up and verify

 

Am I right with the above steps? 

 

Thanks & regards,

 

Hi all,

 

I wish to remove a disk from array to use as back up disk.  The disk in Question is disk3.  It doesn't contain any data.  I've excess capacity and disk3 is doing nothing except consuming energy. Can I do the following without jeopardizing the whole array:

 

1) Stop array

2) Unassign disk3

3) Shut down to pull the correct disk

4) Power up and verify

 

Am I right with the above steps?  

 

Thanks & regards,

 

That will simulate a failed drive.  In order to remove the drive you must ALSO set a new initial disk configuration AND then re-calculate parity based on the new configuration.  You do those after you un-assign the disk, but before you subsequently re-start the array.

 

The method used to set a new disk configuration is different based on the unRAID version you are running.

In older releases, there is a "Restore" button which sets a new disk configuration.

In more recent versions, there is an "initconfig" command.

In the very newest beta release, there is also a button under the Utils tab for a "New Config"

 

After setting a new disk configuration a new "initial" parity calculation, based on the new disk configuration, will begin when you re-start the array.

Just double check that you have nothing on \\tower\disk3

 

I've deleted things on SD cards and later realized that well I shouldn't.

Removing a disk is a bit of a PITA.  Generally it is better not to add a disk until you need it so that you don't ever want to remove a disk.

 

The reason it is a pain is because unRAID maintains parity across all of the disks in your array.  Empty or not, if the disk has been formatted it contains 1s and 0s and is affecting parity.  When you remove such a disk, unRAID will think it has failed and will simulate its contents (even if it is empty).  It will do such a good job simulating it that it will allow you to write new data to the simulated disk.  unRAID will continue to simulate it until you give it another disk to rebuild onto, and then it will dump its simulated contents onto the new disk.  (Cool eh?  This is what you paid for with unRAID!)

 

So how to you remove a disk when that is what you want to do?  There are two basic ways:

 

1 - (The normal way).  You have to explain to unRAID that you want to dump your old array definition and create an array definition that does not contain the removed disk anymore.

 

2 - (The extraordinary way).  You can trick unRAID by zeroing out the disk you want to remove.  When a disk is COMPLETELY zeros - it is invisible from a parity perspective (if you don't understand how parity works, look in the "Best of the Forums" and you'll find some links that explain it enough detail to understand how a disk of all binary zeros is, in effect, invisibile). Once invisible, you can remove it from the array and then trick unRAID into believing the disk was never in the array in the first place.  This technique has the annoying side effect of losing all content on the disk you are removing, which matters sometimes, but for you this should not be an issue.

 

To remove a disk the normal boring way, here is the "safest" procedure I know:

 

1 - Run a parity check.  Examing all smart reports and syslog for signs of problems.  The danger in this process is that a different disk fails before you can fully rebuild parity, so you want to make sure there are not problems before starting.

 

2 - With array stopped, remove the disk from the array from the devices page.  (You can physically remove the disk from the array by shutting down and removing it.  Doesn't have to be done now.)

 

3 - Depending on the unRAID version, the means to get unRAID to re-initialize the array configuration varies.  Earlier versions had a button called "restore" that did this (I know, bad name, but that's what it did), more recent versions had you run the "initiconfig" command at a telnet sesstion, and the most recent beta versions have a button on the "Utility" page to set the new configuration.  They all do the same thing, however.  They undefine your old array.

 

4 - Go to the main page and rearrange your disks if you want to.  Leaving a hole at disk3 will not bother unRAID, but it might bother you.  This is your chance to do penalty free drive rearranging (except parity of course).  Drive rearranging may require you update your user share definitions for included and excluded disks, but you already knew that.

 

5 - Start the array.  unRAID will rebuild parity.  It will take a while, so this is a good time to go have a Margarita or two (or more ...) and sleep it off.

 

6 - Once parity is built (you did ask for the safe way, right?) you should run a parity check to ensure that the parity build was successful.  Only after you've done a parity check and gotten no sync errors can you trust your array is protected again.

 

DONE

 

If you want to follow the extraordinary approach, here is a link to a post that I created a few moons ago on how to do it - complete with screenshots.  Post back with any questions.  I actually think in your situation I'd follow this procedure.  It should take less time than 2 parity checks and a full parity sync, and be safer to boot because you never lose your parity protection.  And you don't care that the disk contents are being lost - its empty anyway.

 

Removing a drive without losing parity protection

 

Good luck!

Hmmm... Not straight forward as I thought. Knowing me - I'll most likely break something.  I'll scrap together all the computers in the house and use the available storage to do back up.  A pain to do but something I had done before my pre-NAS days.  Can;t afford to buy disk now.  2TB disk is pretty cheap now but I'll wait for 3TB price to drop before buying yet another 2TB disk.

 

Thanks for recommendations.