Relevant telegraf.conf:

[[inputs.diskio]]
  name_templates = ["$ID_FS_LABEL","$DM_VG_NAME/$DM_LV_NAME"]

System info:

$ telegraf --version
Telegraf 1.10.2 (git: HEAD 3303f5c3)
 uname -ar
Linux [REDACTED] 4.4.0-151-generic #178-Ubuntu SMP Tue Jun 11 08:30:22 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

Steps to reproduce:

1. Create a Logival Volume (using LVM) with the name lv-a
2. Let telegraf gather some points
3. Delete the LV lv_a
4. Create a LV with the name lv-b
5. Let telegraf gather some points

Expected behavior:

The new points should have the tag: vg-1/lv-b

Actual behavior:

The new points will have the tag: vg-1/lv-a

Additional info:

This is because linux reuse DM ID. Let's say that the first LV had the DM ID 39 its path would be /dev/dm-39.

When deleting the LV, this dm ID will be freed. Thus linux can (and will) reuse it when we'll create another LV.

However since telegraf use a cache for the device infos (https://github.com/influxdata/telegraf/blob/master/plugins/inputs/diskio/diskio_linux.go#L33). It will always return the lv-a informations.

A solution would be to track DM deletions (see if something is in the cache but not in the device list) and remove it from the cache.