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#!/usr/bin/env bash
# raid.sh - Pure RAID-level logic (testable, no I/O).
# Source after common.sh.
#############################
# Valid-level enumeration
#############################
# Print valid RAID levels for a given disk count, one per line.
# Count <2: nothing printed (single disk = no RAID).
# Count 2: mirror, stripe
# Count 3+: + raidz1
# Count 4+: + raidz2
# Count 5+: + raidz3
raid_valid_levels_for_count() {
local count=$1
[[ $count -lt 2 ]] && return 0
echo mirror
echo stripe
[[ $count -ge 3 ]] && echo raidz1
[[ $count -ge 4 ]] && echo raidz2
[[ $count -ge 5 ]] && echo raidz3
return 0
}
# Return 0 if level is valid for the given disk count, 1 otherwise.
# Empty level with count 1 is valid (no RAID).
raid_is_valid() {
local level=$1 count=$2
if [[ $count -le 1 ]]; then
[[ -z "$level" ]]
return
fi
raid_valid_levels_for_count "$count" | grep -qxF "$level"
}
#############################
# Usable-space computation
#############################
# Print usable bytes for a level given disk count, smallest-disk bytes,
# and total bytes across all disks. Writes nothing and returns 1 for
# unknown levels.
#
# Usage: raid_usable_bytes LEVEL COUNT SMALLEST_BYTES TOTAL_BYTES
raid_usable_bytes() {
local level=$1 count=$2 smallest=$3 total=$4
case "$level" in
mirror) echo "$smallest" ;;
stripe) echo "$total" ;;
raidz1) echo $(( (count - 1) * smallest )) ;;
raidz2) echo $(( (count - 2) * smallest )) ;;
raidz3) echo $(( (count - 3) * smallest )) ;;
*) return 1 ;;
esac
}
# Print fault-tolerance (max number of disks that can fail) for a level
# at the given disk count. Unknown level → return 1.
raid_fault_tolerance() {
local level=$1 count=$2
case "$level" in
mirror) echo $(( count - 1 )) ;;
stripe) echo 0 ;;
raidz1) echo 1 ;;
raidz2) echo 2 ;;
raidz3) echo 3 ;;
*) return 1 ;;
esac
}
#############################
# Preview text
#############################
# Print preview text for a single RAID level. Used by get_raid_level()
# in the fzf preview pane. Calls raid_fault_tolerance and
# raid_usable_bytes for the data lines so the math stays in one place.
# Numeric arguments are unit-agnostic — pass GB if you want GB out.
#
# Usage: raid_preview LEVEL DISK_COUNT TOTAL_GB SMALLEST_GB
# Returns 1 for unknown level (no output).
raid_preview() {
local level=$1 count=$2 total=$3 small=$4
local tol usable
tol=$(raid_fault_tolerance "$level" "$count") || return 1
usable=$(raid_usable_bytes "$level" "$count" "$small" "$total") || return 1
case "$level" in
mirror)
cat <<EOF
MIRROR
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
All disks contain identical copies of data.
Maximum redundancy. Can survive loss of all
disks except one.
Redundancy: Can lose $tol of $count disks
Usable space: ~${usable}GB (smallest disk)
Read speed: Fast (parallel reads)
Write speed: Normal
Best for:
- Boot drives
- Critical data
- Maximum safety
EOF
;;
stripe)
cat <<EOF
STRIPE (RAID0)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
WARNING: NO REDUNDANCY!
Data is striped across all disks.
ANY disk failure = ALL data lost!
Redundancy: NONE
Usable space: ~${usable}GB (all disks)
Read speed: Very fast
Write speed: Very fast
Best for:
- Scratch/temp space
- Replaceable data
- Maximum performance
EOF
;;
raidz1)
cat <<EOF
RAIDZ1 (Single Parity)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
One disk worth of parity distributed
across all disks.
Redundancy: Can lose $tol of $count disks
Usable space: ~${usable}GB ($((count - 1)) of $count disks)
Read speed: Fast
Write speed: Good
Best for:
- General storage
- Good balance of space/safety
EOF
;;
raidz2)
cat <<EOF
RAIDZ2 (Double Parity)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Two disks worth of parity distributed
across all disks.
Redundancy: Can lose $tol of $count disks
Usable space: ~${usable}GB ($((count - 2)) of $count disks)
Read speed: Fast
Write speed: Good
Best for:
- Large arrays (5+ disks)
- Important data
EOF
;;
raidz3)
cat <<EOF
RAIDZ3 (Triple Parity)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Three disks worth of parity distributed
across all disks.
Redundancy: Can lose $tol of $count disks
Usable space: ~${usable}GB ($((count - 3)) of $count disks)
Read speed: Fast
Write speed: Moderate
Best for:
- Very large arrays (8+ disks)
- Archival storage
EOF
;;
*)
return 1
;;
esac
}
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