The Swift `ms` cluster is running Stretch and should be upgraded to Bullseye. Running a new kernel will be a great occasion to revising the `mkfs.xfs` options we're using now.
Most notably we're disabling `finobt` (i.e. the free inode btree) because of free space reporting problems in the past ({T199198}). While disabling `finobt` fixes the problem, I believe it does slow down allocations/deletions especially on old-age filesystems and in general given our pattern of creation/deletion of objects (i.e. thumbnails, the most frequent case)
6/8 Frontends done by 2022-04-27 (the last two are the swiftrepl nodes, which are blocking on T299125 )
Initial host status:
```
mvernon@cumin1001:~$ date; sudo cumin '(A:stretch or A:buster) and A:swift'; sudo cumin 'A:bullseye and A:swift'
Mon 11 Apr 2022 01:23:49 PM UTC
93 hosts will be targeted:
ms-be[2028-2069].codfw.wmnet,ms-be[1028-1033,1035-1071].eqiad.wmnet,ms-fe[2009-2012].codfw.wmnet,ms-fe[1009-1012].eqiad.wmnet
DRY-RUN mode enabled, aborting
No hosts found that matches the query
```
Occasionally-updated host status
```
mvernon@cumin2002:~$ date; sudo cumin '(A:stretch or A:buster) and A:swift'; sudo cumin 'A:bullseye and A:swift'
Mon 30 May 2022 09:50:14 AM UTC
49 hosts will be targeted:
ms-be[2028-2039].codfw.wmnet,ms-be[1028-1033,1035-1039,1043-1058,1060-1067].eqiad.wmnet,ms-fe2009.codfw.wmnet,ms-fe1009.eqiad.wmnet
DRY-RUN mode enabled, aborting
43 hosts will be targeted:
ms-be[2040-2069].codfw.wmnet,ms-be[1040-1042,1068-1071].eqiad.wmnet,ms-fe[2010-2012].codfw.wmnet,ms-fe[1010-1012].eqiad.wmnet
DRY-RUN mode enabled, aborting
```