[ClusterLabs] Q: LVM-activate: "WARNING: You are recommended to activate one LV at a time or use exclusive activation mode."

[heming.zhao at suse.com]

Hello,

If I understand code correctly, it looks there at least have two meanings for this warning:

1. from code comments, it just a noisy, you can ignore it totally:

```
     # We recommend to activate one LV at a time so that this specific volume
     # binds to a proper filesystem to protect the data
     # TODO:
     # Will this warn message be too noisy?  <==== this line
     if [ -z "$LV" ]; then
         ocf_log warn "You are recommended to activate one LV at a time or use exclusive activation mode."
     fi
```

2. also from comments, there are some difficult to check all LVs status in VG.
    So if you use (set up) a complex LVs format, it may won't work as expection.

```
# TODO:
# How can we accurately check if LVs in the given VG are all active?
#
# David:
# If we wanted to check that all LVs in the VG are active, then we would
# probably need to use the lvs/lv_live_table command here since dmsetup
# won't know about inactive LVs that should be active.
#
# Eric:
# But, lvs/lv_live_table command doesn't work well now. I tried the following
# method:
#
# lv_count=$(vgs --foreign -o lv_count --noheadings ${VG} 2>/dev/null | tr -d '[:blank:]')
# dm_count=$(dmsetup --noheadings info -c -S "vg_name=${VG}" 2>/dev/null | grep -c "${VG}-")
# test $lv_count -eq $dm_count
#
# It works, but we cannot afford to use LVM command in lvm_status. LVM command is expensive
# because it may potencially scan all disks on the system, update the metadata even using
# lvs/vgs when the metadata is somehow inconsistent.
#
# So, we have to make compromise that the VG is assumably active if any LV of the VG is active.
#
# Paul:
# VGS + LVS with "-" in their name get mangled with double dashes in dmsetup.
# Switching to wc and just counting lines while depending on the vgname + lvname filter
# in dmsetup gets around the issue with dmsetup reporting correctly but grep failing.
#
# Logic for both test cases and dmsetup calls changed so they match too.
#
# This is AllBad but there isn't a better way that I'm aware of yet.
```

Thanks

On 12/1/20 2:23 AM, Andrei Borzenkov wrote:
> 30.11.2020 15:36, Ulrich Windl пишет:
>> Hi!
>>
>> I configured a shared LVM activation as per instructions (I hope) in SLES15 SP2. However I get this warning:
>> LVM-activate(prm_testVG_activate)[57281]: WARNING: You are recommended to activate one LV at a time or use exclusive activation mode.
>>
>> The configuration is:
>> primitive prm_testVG_activate LVM-activate \
>>          params vgname=testVG vg_access_mode=lvmlockd activation_mode=shared ...
>>
>> And I cloned the primitive. So whare is the problem?
>>
> 
> The comments in RA say
> 
>          # We recommend to activate one LV at a time so that this
> specific volume
>          # binds to a proper filesystem to protect the data
> 
> I have no idea what "binds to a proper filesystem" is supposed to mean.
> My best guess is that it's trying to describe dependency between LVM
> resource and filesystem resource, but in this case I also do not see how
> shared and exclusive activation differ here.
> 
> GIT history does not help, resource was added initially with this warning.
> 
>> Does it mean I have to use parameter "lvname"? If so, dows it mean that step 3 of "PROCEDURE 22.4: CREATING AN LVM-ACTIVATE RESOURCE" is missing the parameter, too?
>>
>> Example given is:
>> root # crm configure primitive vg1 ocf:heartbeat:LVM-activate \
>> params vgname=vg1 vg_access_mode=lvmlockd activation_mode=shared \
>> op start timeout=90s interval=0 \
>> op stop timeout=90s interval=0 \
>> op monitor interval=30s timeout=90s
>>
>> Regards,
>> Ulrich
>>
>>
>>
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