This was a failed attempt to create a mdadm RAID1 xfs filesytem backed by two files on separate NVMe drives (with two separate BTRFS filesystems). Read performance was heavily degraded compared to just reading all files from a single btrfs filesystem.

create-raid1-image-files-for-storing-maverick-ggufs.sh

#!/bin/bash
# Raid1 with XFS should perform well:
#  https://www.phoronix.com/review/linux54-hdd-raid/3
#
# to benchmakr this, first outside llama.cpp we can do:
#   $ sudo sh -c "sync; echo 3 > /proc/sys/vm/drop_caches"
#   $ time b3sum /mnt/gguf-unsloth-maverick/.../.../...1-of-4.gguf
set -euo pipefail
usage() {
    echo " \$ $0 /opt/gguf-unsloth-maverick-backing-1-of-2/disk1.img /cache/gguf-unsloth-maverick-backing-2-of-2/disk2.img"
}
if [ $# -ne 2 ]; then
    echo "Unexpected number of arguments, usage:"
    usage
    exit 1
fi
declare -a files
files=($1 $2)
set -x
for fn in ${files[@]}; do
    if [ -e $fn ]; then
        >&2 echo "File already exists, did not recreate it: $fn"
        continue
    fi
    fallocate -l 160G $fn  # my UD-Q2_K_XL checkout needs ~140GiB
    chattr +C $fn  # <-- this should already disable compression, no need for next line
    #btrfs property set $fn compression no
done
for fn in ${files[@]}; do
    if [ ! -e $fn ]; then
        >&2 echo "Could not create file?: $fn"
        exit 1
    fi
done
lo1=$(sudo losetup --find --show $1)
lo2=$(sudo losetup --find --show $2)
if [ ! -d /mnt/gguf-unsloth-maverick ]; then
    sudo mdadm --create --verbose /dev/md0 --level=raid1 --raid-devices=2 $lo1 $lo2
    sudo mkfs.xfs -s size=4096 /dev/md0
    sudo mkdir /mnt/gguf-unsloth-maverick
fi
sudo mount /dev/md0 /mnt/gguf-unsloth-maverick