Optimize Linux filesystem performance with mount options and I/O schedulers

#!/usr/bin/env bash

set -euo pipefail

# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m'

# Logging functions
log_info() { echo -e "${GREEN}[INFO]${NC} $1"; }
log_warn() { echo -e "${YELLOW}[WARN]${NC} $1"; }
log_error() { echo -e "${RED}[ERROR]${NC} $1"; }

# Usage
usage() {
    echo "Usage: $0 [--device DEVICE] [--scheduler SCHEDULER] [--mount-point PATH] [--fs-type TYPE]"
    echo ""
    echo "Options:"
    echo "  --device      Block device to optimize (default: auto-detect)"
    echo "  --scheduler   I/O scheduler (auto|mq-deadline|kyber|none, default: auto)"
    echo "  --mount-point Mount point to optimize (default: /)"
    echo "  --fs-type     Filesystem type (auto|ext4|xfs, default: auto)"
    echo ""
    echo "Example: $0 --device /dev/sda --scheduler mq-deadline"
    exit 1
}

# Cleanup function
cleanup() {
    log_error "Script failed. Check logs above for details."
    if [[ -f /etc/fstab.backup ]]; then
        log_warn "Original fstab backed up to /etc/fstab.backup"
    fi
    exit 1
}

trap cleanup ERR

# Check prerequisites
if [[ $EUID -ne 0 ]]; then
    log_error "This script must be run as root"
    exit 1
fi

# Parse arguments
DEVICE=""
SCHEDULER="auto"
MOUNT_POINT="/"
FS_TYPE="auto"

while [[ $# -gt 0 ]]; do
    case $1 in
        --device)
            DEVICE="$2"
            shift 2
            ;;
        --scheduler)
            SCHEDULER="$2"
            shift 2
            ;;
        --mount-point)
            MOUNT_POINT="$2"
            shift 2
            ;;
        --fs-type)
            FS_TYPE="$2"
            shift 2
            ;;
        -h|--help)
            usage
            ;;
        *)
            log_error "Unknown option: $1"
            usage
            ;;
    esac
done

# Detect distribution
if [[ -f /etc/os-release ]]; then
    . /etc/os-release
    case "$ID" in
        ubuntu|debian)
            PKG_MGR="apt"
            PKG_UPDATE="apt update"
            PKG_INSTALL="apt install -y"
            ;;
        almalinux|rocky|centos|rhel|ol|fedora)
            PKG_MGR="dnf"
            PKG_UPDATE="dnf check-update || true"
            PKG_INSTALL="dnf install -y"
            ;;
        amzn)
            PKG_MGR="yum"
            PKG_UPDATE="yum check-update || true"
            PKG_INSTALL="yum install -y"
            ;;
        *)
            log_error "Unsupported distribution: $ID"
            exit 1
            ;;
    esac
else
    log_error "Cannot detect distribution"
    exit 1
fi

log_info "Detected distribution: $ID"

# Auto-detect device if not specified
if [[ -z "$DEVICE" ]]; then
    DEVICE=$(findmnt -n -o SOURCE "$MOUNT_POINT" | sed 's/[0-9]*$//')
    if [[ -z "$DEVICE" ]]; then
        log_error "Could not auto-detect device for mount point $MOUNT_POINT"
        exit 1
    fi
fi

# Auto-detect filesystem type if not specified
if [[ "$FS_TYPE" == "auto" ]]; then
    FS_TYPE=$(findmnt -n -o FSTYPE "$MOUNT_POINT")
    if [[ -z "$FS_TYPE" ]]; then
        log_error "Could not auto-detect filesystem type for $MOUNT_POINT"
        exit 1
    fi
fi

log_info "Target device: $DEVICE, Filesystem: $FS_TYPE, Mount point: $MOUNT_POINT"

echo "[1/8] Installing performance monitoring tools..."
$PKG_UPDATE
$PKG_INSTALL sysstat iotop hdparm fio
log_info "Performance tools installed"

echo "[2/8] Checking current I/O scheduler configuration..."
BLOCK_DEV=$(basename "$DEVICE")
if [[ -f "/sys/block/$BLOCK_DEV/queue/scheduler" ]]; then
    CURRENT_SCHEDULER=$(cat "/sys/block/$BLOCK_DEV/queue/scheduler" | grep -o '\[.*\]' | tr -d '[]')
    log_info "Current scheduler for $BLOCK_DEV: $CURRENT_SCHEDULER"
else
    log_warn "Cannot access scheduler for $BLOCK_DEV"
fi

echo "[3/8] Determining optimal I/O scheduler..."
if [[ "$SCHEDULER" == "auto" ]]; then
    if [[ "$BLOCK_DEV" =~ ^nvme ]]; then
        SCHEDULER="none"
        log_info "Detected NVMe device, using 'none' scheduler"
    elif [[ -f "/sys/block/$BLOCK_DEV/queue/rotational" ]] && [[ $(cat "/sys/block/$BLOCK_DEV/queue/rotational") == "0" ]]; then
        SCHEDULER="mq-deadline"
        log_info "Detected SSD, using 'mq-deadline' scheduler"
    else
        SCHEDULER="mq-deadline"
        log_info "Using default 'mq-deadline' scheduler"
    fi
fi

echo "[4/8] Configuring I/O scheduler..."
if [[ -f "/sys/block/$BLOCK_DEV/queue/scheduler" ]]; then
    echo "$SCHEDULER" > "/sys/block/$BLOCK_DEV/queue/scheduler"
    log_info "Set scheduler to $SCHEDULER for $BLOCK_DEV"
else
    log_warn "Cannot set scheduler for $BLOCK_DEV"
fi

echo "[5/8] Making I/O scheduler changes persistent..."
UDEV_RULE_FILE="/etc/udev/rules.d/60-io-scheduler.rules"
cat > "$UDEV_RULE_FILE" << 'EOF'
# Optimize I/O schedulers for different device types
ACTION=="add|change", KERNEL=="sd[a-z]*", ATTR{queue/rotational}=="0", ATTR{queue/scheduler}="mq-deadline"
ACTION=="add|change", KERNEL=="nvme[0-9]n[0-9]", ATTR{queue/scheduler}="none"
EOF
chmod 644 "$UDEV_RULE_FILE"
log_info "Created udev rules for persistent scheduler configuration"

echo "[6/8] Backing up fstab and preparing mount options..."
cp /etc/fstab /etc/fstab.backup
log_info "Backed up /etc/fstab to /etc/fstab.backup"

# Get current mount entry
CURRENT_ENTRY=$(grep " $MOUNT_POINT " /etc/fstab | head -n1)
if [[ -z "$CURRENT_ENTRY" ]]; then
    log_error "Could not find mount entry for $MOUNT_POINT in /etc/fstab"
    exit 1
fi

echo "[7/8] Optimizing filesystem mount options..."
case "$FS_TYPE" in
    ext4)
        log_warn "Using performance-oriented ext4 options. These reduce data safety!"
        NEW_OPTIONS="defaults,noatime,data=writeback,barrier=0,commit=60"
        ;;
    xfs)
        NEW_OPTIONS="defaults,noatime,largeio,inode64,swalloc,logbsize=256k"
        ;;
    *)
        NEW_OPTIONS="defaults,noatime"
        log_warn "Using basic optimization for filesystem type: $FS_TYPE"
        ;;
esac

# Update fstab with new options
DEVICE_PATH=$(echo "$CURRENT_ENTRY" | awk '{print $1}')
DUMP=$(echo "$CURRENT_ENTRY" | awk '{print $5}')
PASS=$(echo "$CURRENT_ENTRY" | awk '{print $6}')

# Remove old entry and add new one
sed -i "\|$MOUNT_POINT|d" /etc/fstab
echo "$DEVICE_PATH $MOUNT_POINT $FS_TYPE $NEW_OPTIONS $DUMP $PASS" >> /etc/fstab

log_info "Updated fstab with optimized mount options: $NEW_OPTIONS"

# Validate fstab syntax
if command -v findmnt >/dev/null; then
    findmnt --verify
    log_info "fstab syntax validated successfully"
fi

echo "[8/8] Configuring readahead optimization..."
CURRENT_RA=$(blockdev --getra "$DEVICE" 2>/dev/null || echo "unknown")
log_info "Current readahead for $DEVICE: $CURRENT_RA"

# Set readahead to 2MB (4096 sectors) for better sequential performance
blockdev --setra 4096 "$DEVICE"
log_info "Set readahead to 4096 sectors (2MB) for $DEVICE"

# Make readahead persistent via udev
cat >> "$UDEV_RULE_FILE" << EOF

# Optimize readahead for performance
ACTION=="add|change", KERNEL=="$BLOCK_DEV", ATTR{queue/read_ahead_kb}="2048"
EOF

log_info "Made readahead optimization persistent"

# Reload udev rules
udevadm control --reload-rules
udevadm trigger

echo ""
log_info "Filesystem performance optimization completed!"
echo ""
echo "Summary of changes:"
echo "- I/O scheduler: $SCHEDULER"
echo "- Mount options: $NEW_OPTIONS"
echo "- Readahead: 2MB"
echo ""
log_warn "A reboot is recommended to apply all optimizations"
echo ""
echo "To verify changes after reboot:"
echo "  cat /sys/block/$BLOCK_DEV/queue/scheduler"
echo "  mount | grep $MOUNT_POINT"
echo "  blockdev --getra $DEVICE"
echo ""
echo "To monitor performance:"
echo "  iostat -x 1"
echo "  iotop"