Using a little used drive from pool as replacement

[Zammo]

So, one of my 3TB drives from my 53TB pool is failing (showing flashing red X on HDD Sentinel), I have a lot of unused space on the pool, approx 11TB. So I have a few drives in the pool with only a few GB on. Instead of buying a new 3TB drive is there any way for me to move off the data off a little used drive in my pool, and then also move across all the 3TB of data from the failing drive on to that drive ? What actually happens if I manually move data in the hidden pool folder to another pool folder on another drive ? Any suggestions on how best to do this ? 

Here is an example of what I mean (poolpart numbers are random, not real).........

Drive1 = PoolPart1342343 - Failing 3TB drive, it is 2.62TB used. 

Drive2 = PoolPart324343 - 4TB drive only has 100gb on. 

Drive3 = PoolPart4534534 - 4TB drive, plenty of space on

So if I were to copy the 100gb from Drive2 to Drive3, leaving Drive2 empty, and then copy all of Drive1 on to Drive2. If so what is the safest method to do this ? Would it automatically keep everything in order ? 

Also, the drives are SnapRaided, would it be safer to copy everything off and hope everything is in tact data wise, or restore from the parity drive ? 

Thanks !!

[Shane]

If the drive's failing but stiil currently readable, then you could just tell DrivePool to Remove it and it will evacuate the data file by file to the rest of the drives in your pool (usually the one(s) with the most free space).

If you're wanting to manually move the content as you describe (e.g. because you're using SnapRaid or because you want it done ASAP and don't have duplication), then as long as you turn off any Balancing and Placement, and stop the StableBit DrivePool service you can safely move* content between the poolparts so long as the internal structure is kept the same (e.g. don't change "pathX\fileY" in "Drive1:\PoolPart1342343\pathX\fileY" to "Drive2:\PoolPart324343\pathX\fileY"). Once you're done you can then restart the service, Remove the drive you manually emptied, and then turn back on any Balancing and Placement.

*Note: for a failing disk with no duplication, instead of doing a "direct" move, I would copy the content to the destination and verify the copies before I deleted any content from the source. This minimises writes to the suspect disk while I'm getting data from it.

"Also, the drives are SnapRaided, would it be safer to copy everything off and hope everything is in tact data wise, or restore from the parity drive ?"

See the SnapRaid FAQ for the "100% safe way to proceed": https://www.snapraid.it/faq#move

[Zammo]

Thanks or your help. So just to clarify, if I click remove on the dying drive, it will automatically move everything from that drive to the others ? I know it gives some options of what to do when clicking remove, anything specific I need to select if I just want to move all data off to another drive in the pool ?

You mention duplication, my failing drive shows up as 2.63tb out of 2.76tb unduplicated, what does this actually mean and would this then mean I can't use the remove function and will have to manually copy the files ? As you say, I won't move, but copy. Does duplication mean like a RAID so everything copied is duplicated ?

Thanks.

[Shane]

Yes, if you click Remove on the dying drive then it will automatically move everything (in the pool) that's on that drive to the other drives (in the pool). You may or may not wish to choose the option of "Force damaged drive removal (unreadable files will be left on the disk)." This will help if the drive has damaged files that can't be read.

However, since you are using SnapRaid, you should instead be incorporating its instructions to safely transfer the files without messing up your parity (Disclaimer: I'm not great with SnapRaid, please double-check this):

1. (turn off DrivePool balancing/placement if you're using it - which you probably aren't using if you're using SnapRaid)
2. (stop DrivePool service)
3. copy files from good Drive2 to good Drive3
4. check with diff, if good (identified as copies) proceed with a sync and continue to next step
5. delete files on good Drive2
6. run a sync
7. copy files from failing Drive1 to good Drive2
8. check with diff, if good (identified as copies) proceed with a sync and continue to next step
9. delete files on failing Drive1
10. run a sync
11. might as well take the failing Drive1 out of the machine at this point - run a secure erase on it if you need/want to - but remember to follow the SnapRaid procedure for removing a data disk from the array
12. (start DrivePool service)
13. (remove the "missing" Drive1)
14. (might need to do a Manage Pool -> Re-measure if DrivePool doesn't do it automatically)
15. (turn on DrivePool balancing/placement if you're using it - which you probably aren't using if you're using SnapRaid)

You can still use Remove on a drive containing unduplicated files; it will still move them to another drive. DrivePool duplication, if enabled, is like RAID1 in that it ensures that duplicated files exist on two or more drives (so that if one drive dies unexpectedly you haven't lost any of the duplicated files that were on it as they will also be on at least one other drive). 2x duplication does use 2x the space of course, and so on. You can turn it on for the entire pool or customise it for specific folders.

[Zammo]

Thanks for your great help. 

Out of curiosity, if I have checked the data on the failing drive and it is okay, if I copy that data to a new drive of the same size, inc the hidden Drive Pool folder, can I just swap drives when my PC is turned off ? 

So for instance, 3TB Drive 1 is failing, so I copy everything across to new 3TB drive, remove old drive, mount new drive to same location, without making any changes in DrivePool ? Or does DrivePool sense it has been changed ?

Thanks again. 

 

[Christopher (Drashna)]

No.  There is some very hidden data that doesn't copy over, really.  But if the new drive is added to the pool, you could copy the contents of the PoolPart folder on the old drive to the PoolPart folder on the new drive.   Just make sure you remeasure after it's done.