Bug 1516035

Summary:	misleading suggestion from `lvchange` when trying to activate a duplicated logical volume.
Product:	Red Hat Enterprise Linux 7	Reporter:	Federico Sun <fsun>
Component:	lvm2	Assignee:	David Teigland <teigland>
lvm2 sub component:	Activating existing Logical Volumes	QA Contact:	cluster-qe <cluster-qe>
Status:	CLOSED WONTFIX	Docs Contact:
Severity:	low
Priority:	unspecified	CC:	agk, fsun, heinzm, jbrassow, msnitzer, prajnoha, zkabelac
Version:	7.4
Target Milestone:	rc
Target Release:	---
Hardware:	x86_64
OS:	Linux
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Fixed In Version:		Doc Type:	If docs needed, set a value
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Last Closed:	2021-02-15 07:31:24 UTC	Type:	Bug
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Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Description Federico Sun 2017-11-21 21:10:06 UTC

Description of problem:

If a disk with a duplicated VG/LV is attached to a RHEL 7.4 server, and running `lvchange` trying to activate this duplicated LV, `lvchange` will suggest the usage of `--select|-S vg_uuid` as if specifying the UUID of the desired VG it will activate the LV:
 
 >Multiple VGs found with the same name: skipping vg_test suggest:`  
 >Use --select vg_uuid=<uuid> in place of the VG name. 

This is a misleading message since `lvchange` doesn't support `--select|-S`.


Version-Release number of selected component (if applicable):

Tested on:

rhel 7.4
kernel 3.10.0-693.el7.x86_64
lvm2-libs-2.02.171-8.el7.x86_64
lvm2-2.02.171-8.el7.x86_64


How reproducible:
always.

Steps to Reproduce:
1. install rhel7.4
2. create a VG named vg_test.
3. create a LV named lv_test1.
4. attach a new disk with same VG/LV name created on another server.
5. run `lvchange`.

Actual results:

two VGs with the same name but different UUID:
# vgs -o +vg_uuid
  VG      #PV #LV #SN Attr   VSize    VFree VG UUID
  vg_test   1   1   0 wz--n- 1020.00m    0  fHPQTa-ITQC-iRip-39Qe-Qqdc-rQrv-dPlccB
  vg_test   1   1   0 wz--n-   <2.00g    0  8teRbr-d6y6-OB34-klgG-PucW-dnu6-iOBfg6

same LV name on both VG:
# lvs
  LV       VG      Attr       LSize    Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv_test1 vg_test -wi------- 1020.00m
  lv_test1 vg_test -wi-a-----   <2.00g


# lvchange -ay /dev/mapper/vg_test-lv_test1
  Multiple VGs found with the same name: skipping vg_test
  Use --select vg_uuid=<uuid> in place of the VG name.

The above message suggests that it will activate the LV if the uuid of the desired VG is specified using `--select`:

 # lvchange -ay /dev/mapper/vg_test-lv_test1 --select vg_uuid=fHPQTa-ITQC-iRip-39Qe-Qqdc-rQrv-dPlccB
  Multiple VGs found with the same name: skipping vg_test
  Use --select vg_uuid=<uuid> in place of the VG name.


The output from `lvchange` regarding the usage of `--select` is misleading.


Expected results:

`lvchange` should not suggest --select|-S since this does not work. Or output something useful like using `vgrename` first.

Comment 2 David Teigland 2018-04-03 16:36:12 UTC

This is also discussed in bug 1378829.  Replacing VG name with --select vg_uuid=<uuid> requires that we create a new reserved symbol+word that the user would need to type in place of the VG name, e.g. a special VG name of "#UUID" could mean that the VG is specified by --select vg_uuid="123".

This is a somewhat confusing and inconsistent use of the --select option, because in this case vg_uuid is the only field that's allowed after --select, and it must match only one VG.  IOW, it's not the normal --select behavior at all.  --select is just being used as a vehicle for passing the uuid.

Say that two VGs have the name "foo".  The first has uuid 123-456-789 and the second has uuid abc-def-ghi.

lvchange -ay foo/test
Error: duplicate VG name foo, specify VG with --select vg_uuid.

lvchange -ay --select vg_uuid=123-456-789 #UUID/test

Or in the case of vgrename,

vgrename foo bar
Error: duplicate VG name foo, specify VG with --select vg_uuid.

vgrename --select vg_uuid=123-456-789 #UUID bar

This seems awkward to use, in addition to being inconsistent with normal --select behavior.  It strikes me that if the user has to type #UUID, why not just type the actual uuid there?, e.g. #123-456-789.  That would mean defining a new rule in which a VG name could be replaced with a VG uuid by typing "#" before it.  The examples above would then be:

lvchange -ay #123-456-789/test

vgrename #123-456-789 bar

Comment 5 RHEL Program Management 2021-02-15 07:31:24 UTC

After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.