lvm cachepool disabled after single error on raid1 - is this by design? or coincidence?

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I setup my computer as follows

Fedora 37 kernel 6.0.17-300.fc37.x86_64
sda - SSD
sdb - SSD
sdc - HDD
sdd - HDD
lvcreate -n root -L50G --type=raid1 rootvg sdc sdd
lvcreate -n rootcache -L10G --type=raid1 rootvg sda sdb
lvcreate -n rootmeta -L20M --type=raid1 rootvg sda sdb
lvconvert --type cache-pool --cachemode writeback --poolmetadata rootmeta rootvg/rootcache
lvconvert --cache --cachepool rootcache rootvg/root

sdb failed and I'm getting the usual "Couldn't find device with uuid" errors

So I thought it would be a good idea to disable caching because it's writeback without a mirror, but it's already disabled ???

lvs -a shows ...

  root                                      rootvg Cwi-aoC-p-  50.00g [root-cache_cpool]         [root-f37_corig]     5.83   6.58                 0.00            
  [root_corig]                              rootvg rwi-aoC---  50.00g                                                                             100.00          
  [root_corig_rimage_0]                     rootvg iwi-aor---  50.00g                                                                                             
  [root_corig_rimage_1]                     rootvg iwi-aor---  50.00g                                                                                             
  [root_corig_rmeta_0]                      rootvg ewi-aor---   4.00m                                                                                             
  [root_corig_rmeta_1]                      rootvg ewi-aor---   4.00m                                                                                             
  [root-cache_cpool]                        rootvg Cwi---C-p-  10.00g                                                 5.83   6.58                 0.00            
  [root-cache_cpool_cdata]                  rootvg Cwi-aor-p-  10.00g                                                                             100.00          
  [root-cache_cpool_cdata_rimage_0]         rootvg iwi-aor---  10.00g                                                                                             
  [root-cache_cpool_cdata_rimage_1]         rootvg Iwi-aor-p-  10.00g                                                                                             
  [root-cache_cpool_cdata_rmeta_0]          rootvg ewi-aor---   4.00m                                                                                             
  [root-cache_cpool_cdata_rmeta_1]          rootvg ewi-aor-p-   4.00m                                                                                             
  [root-cache_cpool_cmeta]                  rootvg ewi-aor-p-  20.00m                                                                             100.00          
  [root-cache_cpool_cmeta_rimage_0]         rootvg iwi-aor---  20.00m                                                                                             
  [root-cache_cpool_cmeta_rimage_1]         rootvg Iwi-aor-p-  20.00m                                                                                             
  [root-cache_cpool_cmeta_rmeta_0]          rootvg ewi-aor---   4.00m                                                                                             
  [root-cache_cpool_cmeta_rmeta_1]          rootvg ewi-aor-p-   4.00m                

If I look at LV status with lvdisplay, I see that root, root-cache_cpool_cdata & rootvg/rootcache are available

but rootvg/rootcache is NOT available

# lvdisplay -a rootvg/root-cache_cpool 2>/dev/null 
  --- Logical volume ---
  Internal LV Name       root-cache_cpool
  VG Name                rootvg
  LV UUID                tb9pyc-ARFp-z2PZ-1OA1-SaZB-cRDw-HFDmGL
  LV Write Access        read/write
  LV Creation host, time, 2023-01-09 11:13:04 +0100
  LV Pool metadata       root-cache_cpool_cmeta
  LV Pool data           root-cache_cpool_cdata
  LV Status              NOT available
  LV Size                10.00 GiB
  Current LE             2560
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto

Is this feature by design to protect data when a writeback cache is no longer mirrored, or is this just a lucky coincidence?


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