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+++ This bug was initially created as a clone of Bug #1987170 +++

Blivet currently sets default chunk size (512 KiB) for all raid levels. RAID 1 doesn't use chunks and when creating a RAID 1 array using mdadm the --chunk option used to be silently ignored but starting with mdadm-4.2-rc1_4 this results in an error and the array is not created so we need to stop setting chunk size when creating RAID 1 arrays.

```
# mdadm --create --run md127 --chunk 512 --level raid1 --raid-devices 2 /dev/sdb1 /dev/sdb2 --metadata=1.0                         
mdadm: specifying chunk size is forbidden for this level
```

Following steps from comment #1

Reproduced on RHEL-9.0.0-20210730.d.3 with python3-blivet-3.4.0-3.el9:                         
                                                                                               
INFO:program:Running [45] mdadm --create /dev/md/root --run --level=raid1 --raid-devices=2 --metadata=default --bitmap=internal --chunk=512 /dev/vda1 /dev/vdb1 ...

Tested on RHEL-9.0.0-20210809.d.2 with python3-blivet-3.4.0-4.el9:                             

INFO:program:Running [71] mdadm --create /dev/md/root --run --level=raid1 --raid-devices=2 --metadata=default --bitmap=internal /dev/vda1 /dev/vdb1 ...

python3-blivet-3.4.0-6.el9 is present in nightly compose RHEL-9.0.0-20210817.8.

Moving to VERIFIED.