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Proper way to delete an active snapshot?

linux-lvm Linda A. Walsh 4 participants 6 messages Aug 30, 2011 – Sep 3, 2011

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#0 lore raw

If you have a snapshot of a volume running... how are you supposed to delete it?

i.e. after you unmount it... if I just do a lvremove, I get a warning about it being an active volume -- so I tried doing a dmsetup remove on it first -- and that stops the warning -- but I just noticed, I had a bunch of inactive 'cow' volume names under 'dmsetup ls', that referred to the old snapshot names.

so I'm guessing that using dmsetup to remove the dev first, then lvremove is NOT the best way to be doing this...(as it results in stuff that needs to be cleaned up...)...

So how do I remove the volume w/o getting warnings about it being 'active'?

(Unless, of course it is still mounted or something lame like that -- I mean I want a warning to actually mean something...otherwise I start ignoring them, which is bad (at least for me..)).

#1 lore raw

Dne 30.8.2011 13:32, Linda A. Walsh napsal(a):

Quoted 11 lines

If you have a snapshot of a volume running... how are you supposed to delete it?

i.e. after you unmount it... if I just do a lvremove, I get a warning about it being
an active volume -- so I tried doing a dmsetup remove on it first -- and that stops the warning -- but I just noticed, I had a bunch of inactive 'cow' volume names under 'dmsetup ls', that referred to the old snapshot names.

lvchange -an vg/snapshot_lv

Does it work for you ?

If so - please post -vvvv trace.

Zdenek

#2 lore raw

Dne 30.8.2011 13:47, Zdenek Kabelac napsal(a):

Quoted 7 lines

Dne 30.8.2011 13:32, Linda A. Walsh napsal(a):

Quoted 6 lines

If you have a snapshot of a volume running... how are you supposed to delete it?

Quoted 8 lines
Quoted 5 lines

i.e. after you unmount it... if I just do a lvremove, I get a warning about it being
an active volume -- so I tried doing a dmsetup remove on it first -- and that stops the warning -- but I just noticed, I had a bunch of inactive 'cow' volume names under 'dmsetup ls', that referred to the old snapshot names.

lvchange -an vg/snapshot_lv

Ooops sorry - ignore this one - as this will work with some not yet release target

Quoted 4 lines

Does it work for you ?

If so - please post -vvvv trace.

So just post only lvremove -vvvv trace please.

It could be udev-related issue.

Zdenek

#3 lore raw
Quoted 14 lines · Zdenek Kabelac

Dne 30.8.2011 13:47, Zdenek Kabelac napsal(a):

Quoted 12 lines

Dne 30.8.2011 13:32, Linda A. Walsh napsal(a):

Quoted 10 lines

If you have a snapshot of a volume running... how are you supposed to delete it?

i.e. after you unmount it... if I just do a lvremove, I get a warning about it being
an active volume -- so I tried doing a dmsetup remove on it first -- and that stops the warning -- but I just noticed, I had a bunch of inactive 'cow' volume names under 'dmsetup ls', that referred to the old snapshot names.

Quoted 6 lines
Quoted 2 lines

lvchange -an vg/snapshot_lv

Ooops sorry - ignore this one - as this will work with some not yet release target

I'm confused.

First I tried:

# lvremove /dev/Home+Space/Home-2011.08.31-02.23.11
Do you really want to remove active logical volume Home-2011.08.31-02.23.11? [y/n]: ^C
 Logical volume Home-2011.08.31-02.23.11 not removed

Then, I tried what you had above:

# lvchange -an /dev/Home+Space/Home-2011.08.31-02.23.11     # lvremove /dev/Home+Space/Home-2011.08.31-02.23.11    
 Logical volume "Home-2011.08.31-02.23.11" successfully removed

Was it not supposed to work?

Quoted 20 lines
Quoted 4 lines

Does it work for you ?

If so - please post -vvvv trace.

So just post only lvremove -vvvv trace please.

It could be udev-related issue.

Zdenek

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#4 lore raw
In reply to Linda A. Walsh
Quoted 11 lines · Linda A. Walsh

If you have a snapshot of a volume running... how are you supposed to delete it?

i.e. after you unmount it... if I just do a lvremove, I get a warning about it being an active volume -- so I tried doing a dmsetup remove on it first -- and that stops the warning -- but I just noticed, I had a bunch of inactive 'cow' volume names under 'dmsetup ls', that referred to the old snapshot names.

so I'm guessing that using dmsetup to remove the dev first, then lvremove is NOT the best way to be doing this...(as it results in stuff that needs to be cleaned up...)... So how do I remove the volume w/o getting warnings about it being 'active'?

I agree that the warning is broken (when LV is not otherwise mounted or open).

I use

/usr/sbin/lvremove -f "$snappath"

in scripts, which suppresses the warning without leaving a mess. I'm not sure what happens if the LV is actually open in that case. Hopefully you get an error.

I am on Centos-5.6

--

	      Stuart D. Gathman <[email protected]>
    Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154

"Confutatis maledictis, flammis acribus addictis" - background song for a Microsoft sponsored "Where do you want to go from here?" commercial.

#5 lore raw
Quoted 14 lines · Stuart D. Gathman
Quoted 11 lines · Linda A. Walsh

If you have a snapshot of a volume running... how are you supposed to delete it?

i.e. after you unmount it... if I just do a lvremove, I get a warning about it being an active volume -- so I tried doing a dmsetup remove on it first -- and that stops the warning -- but I just noticed, I had a bunch of inactive 'cow' volume names under 'dmsetup ls', that referred to the old snapshot names.

so I'm guessing that using dmsetup to remove the dev first, then lvremove is NOT the best way to be doing this...(as it results in stuff that needs to be cleaned up...)... So how do I remove the volume w/o getting warnings about it being 'active'?

Quoted 5 lines

I agree that the warning is broken (when LV is not otherwise mounted or open).

I use

/usr/sbin/lvremove -f "$snappath"

---
Yeah...done that... doesn't feel right

Quoted 4 lines

in scripts, which suppresses the warning without leaving a mess. I'm not sure what happens if the LV is actually open in that case. Hopefully you get an error.

Well...
I wouldn't expect that ... ... seems like -f could be for overcoming a stuck driver -- in which case it might ignore a 'mounted' signal from the kernel... So that's why I asked...

The odd thing -- I used lvchange -- but it wasn't a mirrored or active volume..

I had:
....
Home-2011.08.23-18.00.56 Home+Space -wi-ao 6.49g
Home-2011.08.25-02.13.58 Home+Space -wi-ao 4.07g
*Home-2011.08.31-02.23.11 Home+Space -wi-a- 888.00m
Home-2011.08.31-07.34.53 Home+Space -wi-a- 1.86g
---
The one I removed was the one with the * beside it... The one from yesterday morning didn't get filled up and mounted either...but I still have the diff (maybe I copy it off manually.. rather than trust it to another run of my shell
script from hell..(what started out as a fun project has turned into a personal demon!)...

;-')