RAID Layer

Provides a reliable, high‑capacity RAID5 array with an ext4 filesystem aligned for strong performance and clean rebuilds. The setup uses five drives (~36 TiB usable) with a 512K chunk size, proper RAID alignment, and an internal bitmap to speed up recovery. The ext4 filesystem is tuned for sequential workloads and mounted with lightweight options to keep performance high on small‑board hardware.

RAID layer (mdadm)

• Array: /dev/md0
• Level: raid5
• Devices: 5 (sda–sde)
• Array size: 36.38 TiB (40 TB raw)
• Chunk size: 512K
• Layout: left-symmetric
• Bitmap: internal (faster rebuilds)
• Creation command (reconstructed):

bash

sudo mdadm --create /dev/md0 \
  --level=5 \
  --raid-devices=5 \
  --chunk=512 \
  --bitmap=internal \
  /dev/sda /dev/sdb /dev/sdc /dev/sdd /dev/sde

Filesystem and mount

• Filesystem: ext4 (block size 4096)
• Stripe alignment: stripe=384 (aligned to RAID geometry)
• Mount point: /media/plutus
• fstab entry:

Code

UUID=9ce92a73-c4d2-4693-bbc1-68bc21c5d184 /media/plutus ext4 defaults,noatime,nofail 0 2

• Mount options observed: rw,noatime,stripe=384

Rationale

• ext4 chosen for low CPU overhead on SBCs and mature tooling.
• 512K chunk and stripe alignment tuned for large sequential media workloads.
• Internal bitmap reduces rebuild time and risk on intermittent IO.