Comment 6 for bug 1917414

So I'm running into the same issue as well. It was working a few days ago even when I restarted my rpi 4 8gb also running ubuntu 20.04.
I upgraded today and amongst the packages was ceph-osd. Then the rpi stopped working after a reboot. The last time the pi was upgraded was 2 weeks ago.
This is still just a test cluster so I'm more than happy to do any testing to figure out what's going on here.

2021-03-05T21:15:56.786-0800 ffff8d008040 0 set uid:gid to 64045:167 (ceph:ceph)
2021-03-05T21:15:56.786-0800 ffff8d008040 0 ceph version 15.2.8 (bdf3eebcd22d7d0b3dd4d5501bee5bac354d5b55) octopus (stable), process ceph-osd, pid 3300
2021-03-05T21:15:56.786-0800 ffff8d008040 0 pidfile_write: ignore empty --pid-file
2021-03-05T21:15:56.790-0800 ffff8d008040 1 bdev create path /var/lib/ceph/osd/ceph-3/block type kernel
2021-03-05T21:15:56.790-0800 ffff8d008040 1 bdev(0xaaab170f4000 /var/lib/ceph/osd/ceph-3/block) open path /var/lib/ceph/osd/ceph-3/block
2021-03-05T21:15:56.790-0800 ffff8d008040 1 bdev(0xaaab170f4000 /var/lib/ceph/osd/ceph-3/block) open size 8001561821184 (0x74702400000, 7.3 TiB) block_size 4096 (4 KiB) rotational discard not supported
2021-03-05T21:15:56.790-0800 ffff8d008040 1 bluestore(/var/lib/ceph/osd/ceph-3) _set_cache_sizes cache_size 1073741824 meta 0.4 kv 0.4 data 0.2
2021-03-05T21:15:56.790-0800 ffff8d008040 1 bdev create path /var/lib/ceph/osd/ceph-3/block type kernel
2021-03-05T21:15:56.790-0800 ffff8d008040 1 bdev(0xaaab170f4380 /var/lib/ceph/osd/ceph-3/block) open path /var/lib/ceph/osd/ceph-3/block
2021-03-05T21:15:56.794-0800 ffff8d008040 1 bdev(0xaaab170f4380 /var/lib/ceph/osd/ceph-3/block) open size 8001561821184 (0x74702400000, 7.3 TiB) block_size 4096 (4 KiB) rotational discard not supported
2021-03-05T21:15:56.794-0800 ffff8d008040 1 bluefs add_block_device bdev 1 path /var/lib/ceph/osd/ceph-3/block size 7.3 TiB
2021-03-05T21:15:56.794-0800 ffff8d008040 1 bdev(0xaaab170f4380 /var/lib/ceph/osd/ceph-3/block) close
2021-03-05T21:15:57.082-0800 ffff8d008040 1 bdev(0xaaab170f4000 /var/lib/ceph/osd/ceph-3/block) close
2021-03-05T21:15:57.330-0800 ffff8d008040 0 starting osd.3 osd_data /var/lib/ceph/osd/ceph-3 /var/lib/ceph/osd/ceph-3/journal
2021-03-05T21:15:57.330-0800 ffff8d008040 -1 Falling back to public interface
2021-03-05T21:15:57.350-0800 ffff8d008040 -1 load: jerasure load: lrc load dlopen(/usr/lib/aarch64-linux-gnu/ceph/erasure-code/libec_isa.so): /usr/lib/aarch64-linux-gnu/ceph/erasure-code/libec_isa.so: cannot make segment writable for relocation: Operation not permitted