[linux-lvm] lvdisplay "open" field computing

[Simon ELBAZ]

Hi,

Indeed:

root at sympa:~# swapon -s
Nom de fichier                Type        Taille    Utilisé Priorité
/dev/xvdb1                                 partition    2096124 0    -2
/dev/dm-1                                  partition    2084860 0    -3
root at sympa:~# swapoff /dev/sympa-vg/swap_1
root at sympa:~# lvdisplay
...
   --- Logical volume ---
   LV Path                /dev/sympa-vg/swap_1
   LV Name                swap_1
   VG Name                sympa-vg
   LV UUID                1b59OW-M2yW-PuI1-QN5t-pN0w-6Akl-AnJnNh
   LV Write Access        read/write
   LV Creation host, time sympa, 2019-07-10 11:06:42 +0200
   LV Status              available
   # open                 0
   LV Size                <1,99 GiB
   Current LE             509
   Segments               1
   Allocation             inherit
   Read ahead sectors     auto
   - currently set to     256
   Block device           254:1

root at sympa:~# swapon /dev/sympa-vg/swap_1
root at sympa:~# lvdisplay
...

   --- Logical volume ---
   LV Path                /dev/sympa-vg/swap_1
   LV Name                swap_1
   VG Name                sympa-vg
   LV UUID                1b59OW-M2yW-PuI1-QN5t-pN0w-6Akl-AnJnNh
   LV Write Access        read/write
   LV Creation host, time sympa, 2019-07-10 11:06:42 +0200
   LV Status              available
   # open                 2
   LV Size                <1,99 GiB
   Current LE             509
   Segments               1
   Allocation             inherit
   Read ahead sectors     auto
   - currently set to     256
   Block device           254:1

I wonder if there is a similar tool for regular filesystem types.

Regards


On 11/07/2019 17:17, Zdenek Kabelac wrote:
> Dne 11. 07. 19 v 11:39 Simon ELBAZ napsal(a):
>> Hi,
>>
>> I have setup a Debian 10 VM to understand the issue.
>>
>> root at sympa:~# uname -a
>> Linux sympa 4.19.0-5-amd64 #1 SMP Debian 4.19.37-5 (2019-06-19) 
>> x86_64 GNU/Linux
>> root at sympa:~# lvdisplay /dev/sympa-vg/swap_1
>>    --- Logical volume ---
>>    LV Path                /dev/sympa-vg/swap_1
>>    LV Name                swap_1
>>    VG Name                sympa-vg
>>    LV UUID                1b59OW-M2yW-PuI1-QN5t-pN0w-6Akl-AnJnNh
>>    LV Write Access        read/write
>>    LV Creation host, time sympa, 2019-07-10 11:06:42 +0200
>>    LV Status              available
>>    # open                 2
>>    LV Size                <1,99 GiB
>>    Current LE             509
>>    Segments               1
>>    Allocation             inherit
>>    Read ahead sectors     auto
>>    - currently set to     256
>>    Block device           254:1
>>
>> root at sympa:~# lsof | grep "254,1"
>> root at sympa:~# dmsetup info
>> Name:              sympa--vg-swap_1
>> State:             ACTIVE
>> Read Ahead:        256
>> Tables present:    LIVE
>> Open count:        2
>> Event number:      0
>> Major, minor:      254, 1
>> Number of targets: 1
>> UUID: 
>> LVM-Imuz5YW2OXfsyO2ChOPPLI5flib9YlLi1b59OWM2yWPuI1QN5tpN0w6AklAnJnNh
>>
>> Name:              sympa--vg-root
>> State:             ACTIVE
>> Read Ahead:        256
>> Tables present:    LIVE
>> Open count:        1
>> Event number:      0
>> Major, minor:      254, 0
>> Number of targets: 1
>> UUID: 
>> LVM-Imuz5YW2OXfsyO2ChOPPLI5flib9YlLiJMF1vN1e6TKmfV1rT0fvWJnpViu7BMw5
>>
>> root at sympa:~# lsof | grep swap_1
>>
>> root at sympa:~#
>>
>> Could someone pls give me some hints to verify the "open" value ?
>>
>
> Hi
>
> Have you tried  'swapon -s' ?
>
> From the name I'd have guessed it's an active swapping device (so held 
> open by kernel and not visible by user-space tools like lsof)
>
> 'swapoff' should close opened swapping device (in case you have enough 
> free RAM to live without swap space)
>
> Regards
>
> Zdenek
>
>
>
-- 
Simon Elbaz
@Linagora
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