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Remove Drive Without Moving Files


RussellS

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Hi, I have a 10TB media server with SnapRAID and Drivepool and everything was fine until the other day when I was informed by Hard Disk Sentinel that one of my drives was critical and to back it up and replace immediately. When I came to replace the drive it became apparent that I didn't really understand how drivepool works so even though I stumbled my way through and it is all fine now I just want some information so that I understand it better for next time.

So because I have the pool protected by SnapRAID and also I have the entire pool backed up weekly to a backup server I have file/folder duplication turned off in Drivepool. Having read the DP documentation I now understand that if I select 'Remove' next to one of the pool drives then it will attempt to move the data from that drive to the other drives in the pool before then removing the drive from the pool. However, in my situation I don't want any files moved off the drive because I'm backing it up to another drive and then replacing it or rebuilding the data an the new drive with SnapRAID.

So what I want to know is what is the correct procedure to remove a drive that is still functioning from the pool without DP attempting to move any files around.

I know I can just physically remove the drive from the PC and then DP will show it as missing and then you can just click remove but is this the correct procedure to use.

 

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10 hours ago, RussellS said:

So what I want to know is what is the correct procedure to remove a drive that is still functioning from the pool without DP attempting to move any files around.

As you mentioned, the simplest method is to physically disconnect the drive or take it offline via Windows Disk Management; both will result in DrivePool noticing the disk is missing, allowing you to Remove it without affecting the files - however if you don't rename or remove the poolpart folder (a "hidden" folder on the drive) before reconnecting/onlining the drive again it may be rejoined to the pool.

To pre-empt that issue, you can either rename the poolpart folder before disconnecting/offlining the drive (though this may not be possible if there are any open file handles*) or you can open a command prompt as an administrator and enter the following command:

  • dpcmd ignore-poolpart pooldriveletter poolpartfoldername

where pooldriveletter is the drive letter (including the colon) of the pool - not the poolpart - and poolpartfoldername is the name of the poolpart folder that is on the drive you wish to remove. This will "tag" the poolpart folder so that DrivePool will immediately disconnect the poolpart and also ignore it in future.

For example: dpcmd ignore-poolpart k: PoolPart.9be9560f-2871-4c99-9722-7269f0250cfa

* the commands dpcmd list-open-files and dpcmd force-close-open-files can be useful for dealing with this.

10 hours ago, RussellS said:

However, in my situation I don't want any files moved off the drive because I'm backing it up to another drive and then replacing it or rebuilding the data an the new drive with SnapRAID.

Just a reminder that if you are using SnapRAID with a pool, generally you should turn off balancing for that pool (to prevent DrivePool moving files between volumes).

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On 2/4/2021 at 3:20 AM, Shane said:

As you mentioned, the simplest method is to physically disconnect the drive or take it offline via Windows Disk Management; both will result in DrivePool noticing the disk is missing, allowing you to Remove it without affecting the files - however if you don't rename or remove the poolpart folder (a "hidden" folder on the drive) before reconnecting/onlining the drive again it may be rejoined to the pool.

Thanks for clarifying that, at least I know I was doing the right thing.

 

On 2/4/2021 at 3:20 AM, Shane said:

To pre-empt that issue, you can either rename the poolpart folder before disconnecting/offlining the drive (though this may not be possible if there are any open file handles*) or you can open a command prompt as an administrator and enter the following command:

  • dpcmd ignore-poolpart pooldriveletter poolpartfoldername

where pooldriveletter is the drive letter (including the colon) of the pool - not the poolpart - and poolpartfoldername is the name of the poolpart folder that is on the drive you wish to remove. This will "tag" the poolpart folder so that DrivePool will immediately disconnect the poolpart and also ignore it in future.

For example: dpcmd ignore-poolpart k: PoolPart.9be9560f-2871-4c99-9722-7269f0250cfa

* the commands dpcmd list-open-files and dpcmd force-close-open-files can be useful for dealing with this.

That's really good to know, thanks.

 

On 2/4/2021 at 3:20 AM, Shane said:

Just a reminder that if you are using SnapRAID with a pool, generally you should turn off balancing for that pool (to prevent DrivePool moving files between volumes).

I never thought about that but it makes perfect sense. I assume to turn balancing of by just ticking the box 'Do not balance automatically'.

 

Just one more thing, I am in the process of migrating my backup server from FlexRAID over to SnapRAID/Drivepool and I'm a bit confused about the drive duplication. As I have everything parity protected AND backed up I have no need nor do I want any file or folder duplication done by Drivepool. However as you can see from this  screenshot it is saying duplicating at the bottom and this seemed to take quite a long time considering it's not supposed to be duplicating anything.

497355524_Annotation2021-02-05185924.thumb.png.952c8417a555913d46d024cbfde006ad.png

Also I don't know what it means where the little blue arrows are that says 'Un-duplicated target for rebalancing' when I have auto-rebalancing turned off. I just want to understand what this is telling me because it seems to be saying things contrary to the settings.

The other thing I don't understand is under the pie chart of the storage pool it says 'Unduplicated 1.82GB' and 'Other 9.68TB'.  What does 'Other' actually mean.

 

I'm very confused so would really appreciated some insight so I can understand what it's telling me.

 

Thanks

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According to your screenshot, there aren't any duplicated files. So yeah, that's odd?

If duplication is actually turned off, then DrivePool GUI -> Manage Pool -> File Protection -> Pool file duplication... should be offering to enable it.

If it is instead offering to Disable Duplication, then you should click that that to turn off duplication.

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On 2/8/2021 at 2:12 AM, Shane said:

According to your screenshot, there aren't any duplicated files. So yeah, that's odd?

Yeah, that's what I thought.

 

On 2/8/2021 at 2:12 AM, Shane said:

If duplication is actually turned off, then DrivePool GUI -> Manage Pool -> File Protection -> Pool file duplication... should be offering to enable it.

If it is instead offering to Disable Duplication, then you should click that that to turn off duplication.

'Pool file duplication' does offer to enable it indicating that it is indeed turned off.

 

Going back to my earlier question, in my screenshot where it says 'Unduplicated 1.82GB' and 'Other 9.68TB' what does 'Other' actually mean. It seems a bit vague.

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1 hour ago, RussellS said:

in my screenshot where it says 'Unduplicated 1.82GB' and 'Other 9.68TB' what does 'Other' actually mean. It seems a bit vague.

I have found that 'Other' data can be a number of things.

It can mean that there is additional data on the drive outside of the hidden PoolPart directory. One feature of DrivePool is that you can use an existing drive with files on it, add it to DrivePool, and then DrivePool will add the free space to the pool and list the pre existing files as 'Other' data. I have done this a few times when I wanted to add a drive to DrivePool and then move that pre existing data to the pool later. 

Recently I swapped out an old drive for a new drive. For whatever reason, all of sudden I had a 1.8 TB chunk of data listed as 'Other' data and I knew there were no pre existing files on any of the drives in my DrivePool. On the DrivePool GUI, I noticed that one of my drives was the source of all that 'Other' data, and I knew there were no pre existing files on the drive. Fortunately, I was able to correct this situation by going to Manage Pool>Re-Measure. It takes a while to re-measure my 70 TB pool, but afterwards the 'Other' data listing was correctly read and displayed as either Unduplicated or Duplicated data as expected.

Those are two situations I have encountered with my DrivePool, but there may be other situations as well.

In your screenshot, I see that DrivePool is Duplicating data. I thought you said that you had turned that off on your system. At any rate, I'd let the Duplicating task complete. It has been my experience that your 'Other' data situation will not be corrected by the Duplicating task. But if you run the Manage Pool>Re-Measure task after the Duplicating task is complete, it will probably clear up that situation. At least, that is exactly what happened to me the last few days after I swapped out a drive and got that same 'Other' data situation which I knew was incorrect.

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On 2/9/2021 at 5:25 PM, gtaus said:

Those are two situations I have encountered with my DrivePool, but there may be other situations as well.

Thanks for your advice. As you say I'm sure it will settle down once it's 'sorted itself out'.

On 2/9/2021 at 5:25 PM, gtaus said:

In your screenshot, I see that DrivePool is Duplicating data. I thought you said that you had turned that off on your system. At any rate, I'd let the Duplicating task complete. It has been my experience that your 'Other' data situation will not be corrected by the Duplicating task. But if you run the Manage Pool>Re-Measure task after the Duplicating task is complete, it will probably clear up that situation. At least, that is exactly what happened to me the last few days after I swapped out a drive and got that same 'Other' data situation which I knew was incorrect.

That was what I found most confusing, I do have 'Duplication' turned off but it was still saying 'Duplicating'. It all seems rather confusing. I will do as you say and 'Re-Measure' and see what happens.

 

Thanks for your help.

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If you absolutely need to "eject" a drive from the pool without removing files, that can be done.  Though, we do recommend doing it the normal way. 

Specifically, you can use the "dpcmd ignore-poolpart".  This ejects the disk from the pool without moving the files, and causes the disk to show up as "missing" in the UI.  There is the "unignore-poolpart" command that can be used to re-add it, if needed. 

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I really like this feature.  Thanks for having it.   It was useful for me because ...

Spent a couple of days intermittently wondering why a pool wouldn't come back properly.  Remeasuring is just taking forever (days!) but hd-sentinel shows drives all healthy.  Accessing drives individually was fast-ish.  Couldn't tell whether any lag I experienced was because of it being bogged down by remeasure or if it's really slow.  I even have new hard drive enclosures in my cart ready for a purchase!

Finally, came across this thread and decided to eject a member (had my suspicions) and the pool is blazing (albeit missing the files of this drive of course)!  But, in my situation, a semi working pool is better than a non working pool.   Now I can work on this bad drive separately.  i.e. scandisk, recovering files, whatever.   

In hindsight, I suppose I could've physically ejected it, but this gives a nice flexible troubleshooting technique for these half broken mysterious sort of , but not really broken drives I guess.  

Edited by miwa124
clarification
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