Few questions - generally "cant be there a situation where adding the param can harm"?

- on systems without LVM cluster, the option does not harm and is basically just ignored, right?

- should we add that parameter every time, or e.g. by default yes and have an option to fall over to current behaviour?

- is the option available for all versions of all the commands (in case the change backports automatically to e.g. CentOS, older Fedora or similar)?

- is that option available on all platforms (I guess so)? In all distros (at least Ubuntu/Debian)?


Thanks in advance for the answers.


(Technically, this is not RFE - no new feature is requested, just amending few commands collected by sosreport. So I updated the Subject and removed the keyword)

(In reply to Pavel Moravec from comment #2)

Hi, Pavel. Chad asked me to have a look at this.

These are all valid questions. I think the simplest and safest approach would be to add a predicate to test whether the `--foreign` option is available, as we did in https://github.com/sosreport/sos/pull/2127. I don't have any other distros spun up besides Fedora and RHEL.

I believe that the `--foreign` option and the `systemid` field were added throughout LVM2 at the same time. This is in contrast to PR 2127, where we found that `--nolocking` was added to pvs/vgs/lvs before it was added to vgdisplay, etc. :/
  - Add lvmlockd (https://github.com/lvmteam/lvm2/commit/fe70b03d)
  - https://github.com/lvmteam/lvm2/blob/master/tools/lvmcmdline.c#L2471
  - https://github.com/lvmteam/lvm2/blob/master/lib/metadata/metadata.c#L3944

On RHEL, I think it's available starting with RHEL 7.2 (based on the upstream commit's backport tag and on the changelog here: https://access.redhat.com/downloads/content/lvm2/2.02.130-5.el7/x86_64/fd431d51/package-changelog).

---

> Few questions - generally "cant be there a situation where adding the param
> can harm"?
> 
> - on systems without LVM cluster, the option does not harm and is basically
> just ignored, right?

As far as I can tell, that's correct. I tested on my Fedora system, which does NOT have lvm2-lockd (or lvm2-cluster) installed. It worked fine. It didn't change the output or cause any errors.

---

> - should we add that parameter every time, or e.g. by default yes and have
> an option to fall over to current behaviour?

IMO there is no particular reason to create an option to disable the `--foreign` option. But we could do that.

> on systems without LVM cluster, the option does not harm and is basically just ignored, right?

We may want a storage/LVM subject matter expert to weigh in here, but I do not believe that the additional options will cause any harm, especially since metadata_read_only is set, ensuring that no operations that change on-disk metadata are permitted. I wasn't entirely sure that the options would be recognized by older versions of RHEL, so I tried them out on the other VMs that I have access to right away:


RHEL 7 (with cluster):

[root@z1 ~]# lvs -a -o+lv_tags,devices,lv_kernel_read_ahead,lv_read_ahead,stripes,stripesize --config 'global {locking_type = 0 metadata_read_only = 1}' --foreign
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  LV       VG           Attr       LSize    Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert LV Tags Devices        KRahead Rahead #Str Stripe
  ha_lv_01 ha_vg_rh7_01 -wi------- 1020.00m                                                             /dev/sda1(0)        -1   auto    1     0 
  root     rhel         -wi-ao----    9.79g                                                             /dev/vda2(307)   4.00m   auto    1     0 
  swap     rhel         -wi-ao----   <1.20g                                                             /dev/vda2(0)     4.00m   auto    1     0 
[root@z1 ~]# vgs -v -o+vg_mda_count,vg_mda_free,vg_mda_size,vg_mda_used_count,vg_tags,systemid --config 'global {locking_type = 0 metadata_read_only = 1}' --foreign
    Reloading config files
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  VG           Attr   Ext   #PV #LV #SN VSize    VFree VG UUID                                VProfile #VMda VMdaFree  VMdaSize  #VMdaUse VG Tags   System ID
  ha_vg_rh7_01 wz--n- 4.00m   1   1   0 1020.00m    0  pr33Md-RLnU-CMDk-LdWW-mfgR-e0HE-BXzOX3              1   508.00k  1020.00k        1 pacemaker          
  rhel         wz--n- 4.00m   1   2   0  <11.00g 4.00m PnmR5Y-MV0I-Ficf-v0yr-qKhs-iLbg-SzDMP0              1   508.00k  1020.00k        1                    
    Reloading config files



RHEL 7 (no cluster add-on):

[root@testboxcnewsom ~]# lvs -a -o+lv_tags,devices,lv_kernel_read_ahead,lv_read_ahead,stripes,stripesize --config 'global {locking_type = 0 metadata_read_only = 1}' --foreign
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  LV    VG    Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert LV Tags Devices                   KRahead Rahead #Str Stripe
  home  rhel  -wi-ao---- 174.00g                                                             /dev/sda2(2016)             4.00m   auto    1     0 
  root  rhel  -wi-ao----  50.00g                                                             /dev/sda2(46561)            4.00m   auto    1     0 
  swap  rhel  -wi-ao----  <7.88g                                                             /dev/sda2(0)                4.00m   auto    1     0 
  lv_01 vg_01 -wi-ao---- 149.05g                                                             /dev/sdc1(0),/dev/sdb1(0)   4.00m   auto    2  4.00k
[root@testboxcnewsom ~]# vgs -v -o+vg_mda_count,vg_mda_free,vg_mda_size,vg_mda_used_count,vg_tags,systemid --config 'global {locking_type = 0 metadata_read_only = 1}' --foreign
    Reloading config files
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
    Scanning all devices to initialize lvmetad.
  VG    Attr   Ext   #PV #LV #SN VSize    VFree  VG UUID                                VProfile #VMda VMdaFree  VMdaSize  #VMdaUse VG Tags System ID
  rhel  wz--n- 4.00m   1   3   0  231.88g  4.00m i5dDD0-s9iF-FOxd-llSh-d4CW-cjkc-QbZG2D              1        0   1020.00k        1                  
  vg_01 wz--n- 4.00m   2   1   0 <223.54g 74.48g 1t8Sfz-jkaE-Nhiy-P2nX-eqkK-CpXB-g3WH7f              2        0   1020.00k        2                  
    Reloading config files



[root@rhel6-rg-node1 ~]# lvs -a -o+lv_tags,devices,lv_kernel_read_ahead,lv_read_ahead,stripes,stripesize --config 'global {locking_type = 0 metadata_read_only = 1}' --foreign
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  LV        VG         Attr       LSize    Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert LV Tags Devices         KRahead Rahead #Str Stripe
  lv_gfs2_1 vg_gfs2    -wi-ao----    1.00g                                                             /dev/sda1(0)    128.00k   auto    1     0 
  lv_gfs2_1 vg_gfs2    -wi-ao----    1.00g                                                             /dev/sdb1(0)    128.00k   auto    1     0 
  lv_gfs2_2 vg_gfs2    -wi-ao---- 1016.00m                                                             /dev/sdb1(1)    128.00k   auto    1     0 
  lv_root   vg_rhel6rg -wi-ao----    8.51g                                                             /dev/vda2(0)    128.00k   auto    1     0 
  lv_swap   vg_rhel6rg -wi-ao----    1.00g                                                             /dev/vda2(2178) 128.00k   auto    1     0 
[root@rhel6-rg-node1 ~]# vgs -v -o+vg_mda_count,vg_mda_free,vg_mda_size,vg_mda_used_count,vg_tags,systemid --config 'global {locking_type = 0 metadata_read_only = 1}' --foreign
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
    Using volume group(s) on command line.
  VG         Attr   Ext   #PV #LV #SN VSize VFree VG UUID                                VProfile #VMda VMdaFree  VMdaSize  #VMdaUse VG Tags System ID
  vg_gfs2    wz--nc 4.00m   2   2   0 1.99g    0  wioGIf-s4mt-RP0E-fmFN-X6C8-jwJA-s1DeBA              2    61.50k   128.00k        2                  
  vg_rhel6rg wz--n- 4.00m   1   2   0 9.51g    0  1yA8Ac-fzMb-obsr-SMBB-fRm6-a1yn-i5e4EM              1   508.00k  1020.00k        1                  
    Reloading config files
    Wiping internal VG cache


> should we add that parameter every time, or e.g. by default yes and have an option to fall over to current behaviour?

I believe we should, if systemid is not set, it will just be blank similar to the Tags option when a tag is not set. Additionally the "--foreign" option may prove to be helpful to sbr-storage as well (i.e. if a VG is no longer visible and the customer doesn't know why)


> is the option available for all versions of all the commands (in case the change backports automatically to e.g. CentOS, older Fedora or similar)?


I've checked with all of the currently supported major releases of RHEL, but cannot immediately verify on older versions of CentOS or Fedora


> is that option available on all platforms (I guess so)? In all distros (at least Ubuntu/Debian)?

Seems to be present in this debian man page:

https://manpages.debian.org/buster/lvm2/vgs.8.en.html

but not in this ubuntu man page from 16.04 LTS, but it seems to still work. I spun up a ubuntu 16.04 live image and "--foreign" seems to work for pvs, vgs, and lvs. and -o+systemid seems to work for vgs:

http://manpages.ubuntu.com/manpages/xenial/man8/vgs.8.html

Thanks for detailed feedback. I raised:

https://github.com/sosreport/sos/pull/2202

Please review it if it matches desired plans (I followed #c0 that changes collected commands from:

vgdisplay -vv --config="global{locking_type=0 metadata_read_only=1}"
vgscan -vvv --config="global{locking_type=0 metadata_read_only=1}"
pvscan -v --config="global{locking_type=0 metadata_read_only=1}"
pvs -a -v -o +pv_mda_free,pv_mda_size,pv_mda_count,pv_mda_used_count,pe_start --config="global{locking_type=0 metadata_read_only=1}"
vgs -v -o +vg_mda_count,vg_mda_free,vg_mda_size,vg_mda_used_count,vg_tags --config="global{locking_type=0 metadata_read_only=1}"
lvs -a -o +lv_tags,devices,lv_kernel_read_ahead,lv_read_ahead,stripes,stripesize --config="global{locking_type=0 metadata_read_only=1}"

to:

vgdisplay -vv --config="global{locking_type=0 metadata_read_only=1}" --foreign
vgscan -vvv --config="global{locking_type=0 metadata_read_only=1}"
pvscan -v --config="global{locking_type=0 metadata_read_only=1}"
pvs -a -v -o +pv_mda_free,pv_mda_size,pv_mda_count,pv_mda_used_count,pe_start --config="global{locking_type=0 metadata_read_only=1}" --foreign
vgs -v -o +vg_mda_count,vg_mda_free,vg_mda_size,vg_mda_used_count,vg_tags,systemid --config="global{locking_type=0 metadata_read_only=1}" --foreign
lvs -a -o +lv_tags,devices,lv_kernel_read_ahead,lv_read_ahead,stripes,stripesize --config="global{locking_type=0 metadata_read_only=1}" --foreign

I.e.:
- *scan commands are the same
- vgdisplay, pvs and lvs have --foreign
- vgs has --foreign and systemid

)

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (sos bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2021:1604