WHAT: This post is dedicated to preserving the valuable server administration guide content produced by @tjkreidl, originally titled "A Tale of Two Servers." These articles were first published in 2019 on the Citrix Blogs, which are unfortunately no longer available.

KUDOS: Special thanks to @john.c for performing some incredible web sleuthing to recover this content, and to @tjkreidl for creating these essential guides in the first place — as well as for "Breathing Life" back into them by highlighting their importance before they disappeared forever into the ferocious "Bit-Bucket."

Series Overview & Quick Reference

If you're looking for a high-level summary of the concepts covered in this series — including specific XCP-ng/XO commands for BIOS power management, GPU scheduling, and NUMA inspection — start here:
Quick Reference & Summary Guide

The Complete Series

=========================================

Part 1: How BIOS Settings Can Affect Your Apps and GPU Performance:

A deep dive into CPU Power Management (OS DBPM vs. System DBPM) and Turbo mode.
Read Article

Part 2: GPU Settings and Advanced BIOS Tuning

Exploring Uncore frequency, C1E states, and NVIDIA GPU Scheduler modes (Best Effort vs. Equal Share).
Read Article

Part 3: NUMA, CPUs, Sockets/Cores, and VM Performance

Understanding vNUMA, vCPU oversubscription, and the importance of VM startup order for optimal memory placement.
Read Article

Archived for the XCP-ng community. Questions or additional insights? Please discuss below!

@poddingue FYI: I posted the "Feature Request" to the feedback channel here as you suggested.
Hopefully if enough people were used to the way VMware allowed "multiple granular permissions to be set per VM", it will get some traction. Thanks again for pointing me in the right direction.
Happy Day

@poddingue Thank you for the feedback, and suggestion. I will post a request regarding the one-ACL-per-VM issue, as I know it's an issue with our current 600+ VM VMware-to-XCP-ng migration project. Happy Day

@tjkreidl Found it. I re-posted the topic back to the hardware category (and linked the pdf's to the #tobiaskreidl github) here:
Server Admin Guide: A Tale of Two Servers: BIOS, GPU, and NUMA Tuning for XCP-ng: Preserving the valuable work done by Tobias Kreidl (@tjkreidl)

@john.c Will do - and kudos to you on some phenomenal sleuthing work (and to @tjkreidl for sparking ithis contents recall from an early "bit-bucket" grave)! Happy Day All!

@john.c FYI: Bundling/done (Plugin/To come...)

UPDATE: Tag-Based Automation Plugin is now available

####(click here for new thread)

===================================

IMPORTANT: THE FOLLOWING IS OLD/LEGACY CODE

(Use the link above link for the new XO plugin instead)

---

UPDATE: Tag-Based-Automation-Bundle v1.0

WHAT'S NEW: This update introduces the "Tag-Based-Automation" bundle -- a modular, install.sh-based package that replaces the original standalone set-performance.sh script.

This bundle is the foundation for the upcoming "Tag-Based-Automation" plugin for Xen Orchestra (if/when all that gets worked out with Vates).
For now it is a production-ready shell-based bundle that installs cleanly on all XCP-ng pool hosts, and will only run on the current Pool Master.

The goal is simple: Metadata (Tags) should drive Infrastructure State.

STANDARD DISCLAIMER HERE

This software is provided "AS-IS" without any express or implied warranty. While these scripts are being used in a production environment managing VMs, you should always review the code and test it in a non-production environment before full deployment.
Note: The scripts are designed to ONLY take action on VMs with specific tags assigned -- untagged VMs are never touched.
That said, as always - your mileage may vary...

WHAT IS IN THE BUNDLE?

[ACTIVE]      set-performance.sh
              Automated enforcement of CPU weights and I/O priorities
              based on assigned VM tags. Runs via cron. Prevents
              configuration drift across your entire pool.

[COMING SOON] Manage Tags via CSV
              Bulk VM metadata management using a CSV as Source of
              Truth workflow. Export your VM list, edit tags in Excel,
              sync back to the pool in one command.

[COMING SOON] set-permissions.sh
              Automated management of Xen Orchestra Resource Sets and
              user permissions -- driven entirely by your existing VM
              tags. No manual Resource Set updates ever again.

CHANGE-LOG

v1.0 - 2026-05-16 (Bundle Release)
  - Modular Architecture: Repackaged as a modular bundle for easier
    updates and future plugin development
  - One-Shot Installer: install.sh handles directory creation,
    permissions, and legacy standalone cleanup detection
  - Orchestrator: main.sh manages module execution and cron
    scheduling via symlink -- no manual crontab editing required
  - Dual Config System: default.conf (never edit) + custom.conf
    (your pool settings) -- your settings are preserved on re-install
  - NFS Integration: Optional log aggregation for centralized
    reporting across multiple pools
  - Master Host Check: Robust UUID comparison ensures script only
    runs on the Pool Master -- safe to deploy on all hosts
  - Foundation for upcoming Xen Orchestra plugin

v3.2 - 2026-05-14 (Final Standalone Release)
  - Fixed Master Host Check: Replaced invalid xe host-is-master
    with correct UUID comparison method

v3.1 - 2026-05-14
  - Config Separation: Moved to conf.d/ override pattern
  - Split into default.conf and custom.conf

v3.0 - 2026-05-14
  - TAG_SUFFIX support for multi-pool deployments
  - Auto-scheduling via initialize -- no manual crontab needed

v2.0 - 2026-05-14
  - External configuration file
  - Master Host Check (first attempt)
  - Main log + summary log
  - Per-tier summary counters

v1.0 - Initial Release
  - Tag-based CPU weight and I/O priority enforcement
  - Four tiers: 0-core, 1-high, 2-normal, 3-low
  - Network QoS cap (100Mbps) for 3-low tagged VMs

CLEANUP: REMOVING THE OLD STANDALONE VERSION (If installed)

If you installed the original standalone script, run these first:

  rm -f /usr/local/bin/set-performance.sh
  rm -rf /usr/local/etc/set-performance.conf.d
  rm -f /etc/cron.hourly/set-performance
  rm -f /etc/cron.daily/set-performance
  rm -f /etc/cron.weekly/set-performance
  rm -f /etc/cron.monthly/set-performance

DOWNLOAD (Recommended)

Download the v1.0 bundle directly from GitHub:
https://github.com/johnezero/xo-tag-automation/releases/download/v1.0/tag-automation-v1.0.tar.gz

INSTALLING THE BUNDLE

STEP 1: Download and extract on your Pool Master

wget https://github.com/johnezero/xo-tag-automation/releases/download/v1.0/tag-automation-v1.0.tar.gz
tar -xzvf tag-automation-v1.0.tar.gz
cd tag-automation-bundle/

-- OR --

Download to your workstation and upload via SCP or WinSCP:
scp tag-automation-v1.0.tar.gz root@your-pool-master:/root/
Then on your Pool Master:
tar -xzvf tag-automation-v1.0.tar.gz
cd tag-automation-bundle/

STEP 2: Run the installer
chmod +x install.sh
./install.sh

The installer will:
- Detect and warn about any legacy standalone components
- Create all required directories
- Deploy all scripts and config files
- Preserve any existing custom.conf on re-install
- Verify your NFS code path if applicable

STEP 3: Edit your pool-specific config:
*** ACTION REQUIRED -- DO NOT SKIP ***
vi /usr/local/etc/tag-automation/conf.d/custom.conf

Set your TAG_SUFFIX to match your pool:
POOL-1 --> TAG_SUFFIX="-1"
POOL-2 --> TAG_SUFFIX="-2"
Single pool --> TAG_SUFFIX=""

STEP 4: Initialize the bundle (REQUIRED):
*** ACTION REQUIRED -- DO NOT SKIP ***
/usr/local/bin/tag-automation/main.sh initialize

Expected output:
[OK] Symlink created : /etc/cron.hourly/tag-automation
[OK] Schedule : hourly
[OK] Tag suffix : (none)
[OK] Active tags : 0-core, 1-high, 2-normal, 3-low
[OK] Performance : true
[--] Permissions : Coming Soon

*** Bundle will NOT run until initialize is completed ***

STEP 5: Verify it is working
/usr/local/bin/tag-automation/main.sh
tail /var/log/tag-automation.log
tail /var/log/tag-automation-summary.log

THE FILES (i.e. The hard way)

1-of-5: install.sh
Note: The install bundle can e located anywhere (i.e. /root/tag-automation-bundle)

--------------------------------------------

#!/bin/bash

# ============================================
# Tag-Based-Automation -- install.sh (v1.1)
# One-shot installer for the full bundle
# ============================================

BUNDLE_DIR="$(dirname "$0")"
INSTALL_BIN="/usr/local/bin"
INSTALL_CONF="/usr/local/etc"

echo ""
echo "Tag-Based-Automation -- Installer v1.1"
echo "============================================"
echo ""

if [ "$(id -u)" != "0" ]; then
    echo "Error: This installer must be run as root."
    exit 1
fi

if ! command -v xe &>/dev/null; then
    echo "Error: xe command not found."
    echo "This installer must be run on an XCP-ng Pool Master."
    exit 1
fi

echo "Checking for legacy standalone components..."
LEGACY_FOUND=false

[ -f "/usr/local/bin/set-performance.sh" ] && \
    echo "  [!] Legacy script found: /usr/local/bin/set-performance.sh" && \
    LEGACY_FOUND=true

[ -d "/usr/local/etc/set-performance.conf.d" ] && \
    echo "  [!] Legacy config dir found: /usr/local/etc/set-performance.conf.d" && \
    LEGACY_FOUND=true

crontab -l 2>/dev/null | grep -q "set-performance.sh" && \
    echo "  [!] Legacy crontab entry detected." && \
    LEGACY_FOUND=true

LEGACY_CRONS=$(find /etc/cron.hourly /etc/cron.daily /etc/cron.weekly \
    /etc/cron.monthly -name "set-performance" 2>/dev/null)
if [ -n "$LEGACY_CRONS" ]; then
    echo "  [!] Legacy cron symlinks detected:"
    echo "$LEGACY_CRONS" | sed 's/^/      - /'
    LEGACY_FOUND=true
fi

if [ "$LEGACY_FOUND" = true ]; then
    echo ""
    echo "-----------------------------------------------------------------------"
    echo "CAUTION: Legacy standalone components detected."
    echo "Please remove them before proceeding:"
    echo ""
    echo "  rm -f /usr/local/bin/set-performance.sh"
    echo "  rm -rf /usr/local/etc/set-performance.conf.d"
    echo "  rm -f /etc/cron.hourly/set-performance"
    echo "  rm -f /etc/cron.daily/set-performance"
    echo "  rm -f /etc/cron.weekly/set-performance"
    echo "  rm -f /etc/cron.monthly/set-performance"
    echo "-----------------------------------------------------------------------"
    echo ""
    read -p "Abort to clean up manually? (Y/n): " choice
    case "$choice" in
      n|N ) echo "Proceeding with caution -- watch for conflicts!"; echo "" ;;
      * )   echo "Installation aborted. Clean up and re-run install.sh."; exit 1 ;;
    esac
else
    echo "[OK] No legacy components found -- clean install!"
    echo ""
fi

echo "Creating directory structure..."
mkdir -p "$INSTALL_BIN/tag-automation/modules"
mkdir -p "$INSTALL_CONF/tag-automation/conf.d"
echo "[OK] Directories created"

echo "Installing main.sh..."
cp "$BUNDLE_DIR/main.sh" "$INSTALL_BIN/tag-automation/main.sh"
chmod +x "$INSTALL_BIN/tag-automation/main.sh"
echo "[OK] main.sh installed"

echo "Installing modules..."
cp "$BUNDLE_DIR/modules/set-performance.sh" \
   "$INSTALL_BIN/tag-automation/modules/set-performance.sh"
chmod +x "$INSTALL_BIN/tag-automation/modules/set-performance.sh"
echo "[OK] set-performance.sh installed"
echo "[--] set-permissions.sh -- Coming Soon (not installed)"

echo "Installing configuration files..."
cp "$BUNDLE_DIR/conf.d/default.conf" \
   "$INSTALL_CONF/tag-automation/conf.d/default.conf"
echo "[OK] default.conf installed"

if [ ! -f "$INSTALL_CONF/tag-automation/conf.d/custom.conf" ]; then
    cp "$BUNDLE_DIR/conf.d/custom.conf" \
       "$INSTALL_CONF/tag-automation/conf.d/custom.conf"
    echo "[OK] custom.conf installed (first time)"
else
    echo "[OK] custom.conf already exists -- skipping (your settings preserved)"
fi

NFS_CODE_PATH="/mnt/v0/code/tag-automation"
if [ -d "$NFS_CODE_PATH" ]; then
    mkdir -p "$NFS_CODE_PATH/logs"
    echo "[OK] NFS code path verified : $NFS_CODE_PATH"
else
    echo "[--] NFS code path not found: $NFS_CODE_PATH"
    echo "     mkdir -p $NFS_CODE_PATH/logs"
fi

echo ""
echo "============================================"
echo "  *** ACTION REQUIRED -- DO NOT SKIP ***"
echo "============================================"
echo ""
echo "  STEP 1: Edit your pool-specific config:"
echo "    vi $INSTALL_CONF/tag-automation/conf.d/custom.conf"
echo ""
echo "    Set your TAG_SUFFIX to match your pool:"
echo "      POOL-1 --> TAG_SUFFIX=\"-1\""
echo "      POOL-2 --> TAG_SUFFIX=\"-2\""
echo "      Single pool --> TAG_SUFFIX=\"\""
echo ""
echo "  STEP 2: Initialize the bundle (REQUIRED):"
echo "    /usr/local/bin/tag-automation/main.sh initialize"
echo ""
echo "  STEP 3: Verify it is working:"
echo "    /usr/local/bin/tag-automation/main.sh"
echo "    tail /var/log/tag-automation.log"
echo ""
echo "  *** Bundle will NOT run until initialize is completed ***"
echo "============================================"

2-of-5: main.sh

#!/bin/bash

# ============================================
# Tag-Based-Automation -- main.sh (v1.0)
# Orchestrator: loads config, runs modules
# ============================================

CONF_DIR="/usr/local/etc/tag-automation/conf.d"
DEFAULT_CONF="$CONF_DIR/default.conf"
CUSTOM_CONF="$CONF_DIR/custom.conf"
SCRIPT_PATH="/usr/local/bin/tag-automation/main.sh"

if [ -f "$DEFAULT_CONF" ]; then
    source "$DEFAULT_CONF"
else
    echo "Error: default.conf not found at $DEFAULT_CONF"
    exit 1
fi
[ -f "$CUSTOM_CONF" ] && source "$CUSTOM_CONF"

CORE_TAG="${CORE_BASE}${TAG_SUFFIX}"
HIGH_TAG="${HIGH_BASE}${TAG_SUFFIX}"
NORMAL_TAG="${NORMAL_BASE}${TAG_SUFFIX}"
LOW_TAG="${LOW_BASE}${TAG_SUFFIX}"

initialize_plugin() {
    echo ""
    echo "Tag-Based-Automation -- Initialization"
    echo "============================================"

    if [ ! -d "$CONF_DIR" ]; then
        echo "Error: Config directory not found: $CONF_DIR"
        exit 1
    fi

    if [ ! -f "$DEFAULT_CONF" ]; then
        echo "Error: default.conf not found."
        exit 1
    fi

    [ ! -f "$CUSTOM_CONF" ] && \
        echo "Warning: custom.conf not found. Using defaults only."

    TARGET_DIR="/etc/cron.${SCHEDULE}"
    SYMLINK_PATH="${TARGET_DIR}/tag-automation"

    if [ ! -d "$TARGET_DIR" ]; then
        echo "Error: Cron directory not found: $TARGET_DIR"
        echo "Valid SCHEDULE options: hourly, daily, weekly, monthly"
        exit 1
    fi

    for interval in hourly daily weekly monthly; do
        rm -f "/etc/cron.${interval}/tag-automation"
    done

    ln -sf "$SCRIPT_PATH" "$SYMLINK_PATH"

    if [ -L "$SYMLINK_PATH" ]; then
        echo "[OK] Symlink created : $SYMLINK_PATH"
        echo "[OK] Schedule        : $SCHEDULE"
        echo "[OK] Tag suffix      : ${TAG_SUFFIX:-(none)}"
        echo "[OK] Active tags     : $CORE_TAG, $HIGH_TAG, $NORMAL_TAG, $LOW_TAG"
        echo "[OK] Performance     : ${ENABLE_PERFORMANCE:-true}"
        echo "[--] Permissions     : Coming Soon"
        echo ""
        echo "Initialization complete. Bundle will run $SCHEDULE via cron."
    else
        echo "Error: Failed to create symlink."
        exit 1
    fi
}

[ "$1" == "initialize" ] && initialize_plugin && exit 0

# --- MASTER HOST CHECK ---
POOL_MASTER=$(xe pool-list params=master --minimal)
LOCAL_HOST=$(xe host-list name-label=$(hostname) --minimal)
[ "$POOL_MASTER" != "$LOCAL_HOST" ] && exit 0

exec >> "$MAIN_LOG" 2>&1
echo "--- Tag-Automation Starting: $(date) ---"
echo "    Tags: $CORE_TAG | $HIGH_TAG | $NORMAL_TAG | $LOW_TAG"

if [ "${ENABLE_PERFORMANCE:-true}" == "true" ]; then
    echo "--- Running set-performance module ---"
    bash /usr/local/bin/tag-automation/modules/set-performance.sh
fi

# --- set-permissions MODULE (COMING SOON) ---
# if [ "${ENABLE_PERMISSIONS:-false}" == "true" ]; then
#     echo "--- Running set-permissions module ---"
#     bash /usr/local/bin/tag-automation/modules/set-permissions.sh
# fi

# --- NFS LOG PUSH (graceful -- no auto-remount) ---
NFS_CODE_PATH="/mnt/v0/code/tag-automation"
if mountpoint -q "/mnt/v0" && [ -d "$NFS_CODE_PATH" ]; then
    cp "$SUMMARY_LOG" "$NFS_CODE_PATH/logs/" 2>/dev/null
    echo "[OK] Logs pushed to NFS"
else
    echo "[--] NFS not available -- skipping log push"
fi

echo "--- Tag-Automation Complete: $(date) ---"
echo "$(date '+%Y-%m-%d %H:%M:%S') $(hostname) Suffix:${TAG_SUFFIX:-(none)} Performance:${ENABLE_PERFORMANCE:-true}" >> "$SUMMARY_LOG"

3-of-5: modules/set-performance.sh

#!/bin/bash

# ============================================
# Tag-Based-Automation Module: set-performance.sh (v3.2)
# Called by main.sh -- inherits all variables
# ============================================

count_0=0
count_1=0
count_2=0
count_3=0

echo "--- Starting Performance Sync: $(date) ---"
echo "    Tags: $CORE_TAG | $HIGH_TAG | $NORMAL_TAG | $LOW_TAG"

echo "=== Applying $CORE_TAG (Weight: $CORE_WEIGHT, Pri: $CORE_IO_PRI) ==="
for uuid in $(xe vm-list tags:contains="$CORE_TAG" --minimal | tr ',' '\n'); do
    [ -z "$uuid" ] && continue
    xe vm-param-set uuid=$uuid VCPUs-params:weight=$CORE_WEIGHT \
        other-config:sched-pri=$CORE_IO_PRI
    echo "  [OK] CORE applied: $uuid"
    ((count_0++))
done

echo "=== Applying $HIGH_TAG (Weight: $HIGH_WEIGHT, Pri: $HIGH_IO_PRI) ==="
for uuid in $(xe vm-list tags:contains="$HIGH_TAG" --minimal | tr ',' '\n'); do
    [ -z "$uuid" ] && continue
    xe vm-param-set uuid=$uuid VCPUs-params:weight=$HIGH_WEIGHT \
        other-config:sched-pri=$HIGH_IO_PRI
    echo "  [OK] HIGH applied: $uuid"
    ((count_1++))
done

echo "=== Applying $NORMAL_TAG (Weight: $NORMAL_WEIGHT, Pri: $NORMAL_IO_PRI) ==="
for uuid in $(xe vm-list tags:contains="$NORMAL_TAG" --minimal | tr ',' '\n'); do
    [ -z "$uuid" ] && continue
    xe vm-param-set uuid=$uuid VCPUs-params:weight=$NORMAL_WEIGHT \
        other-config:sched-pri=$NORMAL_IO_PRI
    echo "  [OK] NORMAL applied: $uuid"
    ((count_2++))
done

echo "=== Applying $LOW_TAG (Weight: $LOW_WEIGHT, Pri: $LOW_IO_PRI) ==="
for uuid in $(xe vm-list tags:contains="$LOW_TAG" --minimal | tr ',' '\n'); do
    [ -z "$uuid" ] && continue
    xe vm-param-set uuid=$uuid VCPUs-params:weight=$LOW_WEIGHT \
        other-config:sched-pri=$LOW_IO_PRI
    echo "  [OK] LOW applied: $uuid"
    ((count_3++))
done

echo "--- Performance Sync Complete: $(date) ---"
echo "$(date '+%Y-%m-%d %H:%M:%S') $(hostname) \
    $CORE_TAG:$count_0 $HIGH_TAG:$count_1 \
    $NORMAL_TAG:$count_2 $LOW_TAG:$count_3" >> "$SUMMARY_LOG"

4-of-5: conf.d/default.conf

# ============================================
# default.conf
# Global defaults for Tag-Based-Automation
# DO NOT edit -- use custom.conf for overrides
# ============================================

SCHEDULE="hourly"

ENABLE_PERFORMANCE=true
# ENABLE_PERMISSIONS=false  # Coming Soon

MAIN_LOG="/var/log/tag-automation.log"
SUMMARY_LOG="/var/log/tag-automation-summary.log"

CORE_BASE="0-core"
HIGH_BASE="1-high"
NORMAL_BASE="2-normal"
LOW_BASE="3-low"

CORE_WEIGHT="2048"
CORE_IO_PRI="7"

HIGH_WEIGHT="1024"
HIGH_IO_PRI="7"

NORMAL_WEIGHT="256"
NORMAL_IO_PRI="4"

LOW_WEIGHT="128"
LOW_IO_PRI="1"

5-of-5: conf.d/custom.conf

# ============================================
# custom.conf
# Pool-specific overrides
# Edit this file to customize your environment
# ============================================

# --- TAG SUFFIX ---
# POOL-1 --> TAG_SUFFIX="-1"
# POOL-2 --> TAG_SUFFIX="-2"
# Generic --> TAG_SUFFIX=""
TAG_SUFFIX=""

# --- OPTIONAL OVERRIDES ---
# Uncomment to override default.conf values:
# SCHEDULE="daily"
# ENABLE_PERFORMANCE=true
# CORE_WEIGHT="4096"
# HIGH_WEIGHT="2048"
# NORMAL_WEIGHT="512"
# LOW_WEIGHT="256"

@poddingue Thank you!
"Anything and Everything we can to to improve XCP-ng", is the "Name of the Game"

@julienXOvates Noted, thank you!

@MathieuRA Wow, and wow! Thanks for the detail on RBAC, I'll have give it a look. Unfortunately the current plugin doesn't get any where near the "deep-weeds" of all that, and basically just uses the built-in "Admin, Operator and Viewer" roles to auto-provision (via Autopilot) new VMs as they show up (i.e. during a migration project, etc. ). We needed something for our current VMware-to-XCP-ng migration project, and '"Where's there's a will, there's a way" kicked in and the plugin came to be.
Thanks again for your input, and let me know if anything else comes to mind...
Happy Day

@poddingue FYI: I posted the "Feature Request" to the feedback channel here as you suggested.
Hopefully if enough people were used to the way VMware allowed "multiple granular permissions to be set per VM", it will get some traction. Thanks again for pointing me in the right direction.
Happy Day

@poddingue Thank you for the feedback, and suggestion. I will post a request regarding the one-ACL-per-VM issue, as I know it's an issue with our current 600+ VM VMware-to-XCP-ng migration project. Happy Day

UPDATE: Tag-Based-Automation Plugin

WHAT: The xo-tag-automation plugin is a native xo-server plugin that enforces VM performance tiers, manages group permissions, and synchronizes VM metadata -- all driven by VM tags and NFS-hosted CSV files (see below for more details). In general only apply one performance and/or permission action tag per VM. Note: Currently XO only allows one ACL assignment per VM (e.g. assigning "Dept1-Operator", and" Dept3-Admin" to the same VM does not work).

So brace yourself as there's a lot to chew below,, but I promise if your actively involved with a sizable migration project like we are (a.k.a. "Who can afford VMware anymore?"), it will be well worth your time once you have the plugin setup and running (especially in the "Set-it and Forget-it" Permissions AutoPiolot mode). Enjoy....

FEATURES

---

PERFORMANCE SYNC
Automatically applies CPU weights and IO priorities (sched-pri) based on VM performance tier tags:

0-core   -- CPU weight: 2048  IO priority: 7
1-high   -- CPU weight: 1024  IO priority: 7
2-normal -- CPU weight: 512   IO priority: 5
3-low    -- CPU weight: 256   IO priority: 2

All tier weights and IO priorities are fully configurable in the plugin UI. An optional pool-specific tag suffix (e.g. -1=POOL1, -2=POOL2, etc.) allows you to manage multiple pools from a single XO instance without tag collisions.
Note: Under normal conditions these performance settings do not affect anything. It's only when system resources are under high-load that the tiering levels ensure important VMs get priority over non-critical workloads, etc.

---

PERMISSION SYNC
VM tags ending in -Admin, -Operator, or -Viewer (e.g. "Dept1-Operator", "Dept2-Admin", etc.) automatically trigger appropriate XO Group creation and ACL assignments for the designated VM.

CSV PERMISSION MANAGEMENT FILES
Two CSV files on your NFS share drive the workflow:

current-vms.csv
A live export of your entire VM inventory. Contains UUID, Name, CurrentTags, NewTags, CurrentNotes, and NewNotes columns. Edit the NewTags and NewNotes columns and run the plugin (e.g. push the [Test plugin] button) to apply changes in bulk. The CSV auto-refreshes after each run. A staleness warning fires if the CSV has not been updated
within a configurable number of days.

preload-vms.csv
Pre-stage tag and notes configurations for VMs that do not exist yet -- before they are migrated or created. The moment a VM matching a preload entry appears in XO, the plugin applies (on next scheduled interval) its tags and notes automatically and removes the entry from the preload file.

---

PERMISSION AUTOPILOT
Designed for active migration and onboarding projects. Automatically applies permission settings on scheduled interval, based on preload-vms.csv contents. Note: Should be disabled when not actively involved in migration projects.

---

DRY-RUN / EXPORT-CSV MODE
When Dry-Run is ON (the default), the plugin previews all changes in the XO logs without applying any changes, and simultaneously exports a fresh copy of all VM metadata to current-vms.csv with blank NewTags and NewNotes columns ready to fill in. Turn Dry-Run OFF to apply changes for real.

---

RUN NOW (e.g. The [Test plugin] button)
Trigger a full enforcement cycle instantly from the XO plugin UI without waiting for the next scheduled run.

---

NFS LOGGING
All activity is written to structured log files on your NFS share:

xo-tag-automation.log         -- full run log (auto-rotates at 2MB)
xo-tag-automation.log.1      -- previous log backup
xo-tag-automation-summary.log -- run summary entries only
daily-summary.log             -- nightly VM count and new VM report

Logs are also available via xo-cli API methods (see below).

---

LEGACY MIGRATION
If you have an existing vm_metadata.csv from an older version, the plugin automatically renames it to current-vms.csv on first run. No manual migration needed.

---

SECURITY -- PLEASE READ CAREFULLY

This plugin automates infrastructure changes. Security is not optional. Please take both of the following seriously before enabling Permission Sync or Autopilot.

---

-- REST API SERVICE ACCOUNT --

This plugin uses the XO JSON-RPC API internally. Use a dedicated service account (never your personal admin credentials). Note: REST API is only required for the Permissions Sync functions, it's not required if you just want to use the Performance Sync plugin functionality.

Recommended setup (generic -- adapt to your environment):

1. Create a dedicated XO user account for the service (e.g. a non-admin account with only the minimal access permissions required)

2. Generate a scoped API token via xo-cli:
   xo-cli --register
   xo-cli token.create

3. Store the token securely -- treat it like a password!

4. Refer to the official Vates REST API documentation for full token management guidance:
   https://xen-orchestra.com/docs/restapi.html

---

-- NFS SHARE SECURITY --

The NFS share hosts your CSV files and logs. Anyone with write access to the share can modify VM tags and permissions.

STRONGLY RECOMMENDED

• Run the NFS share from a dedicated VM -- not a general-purpose NFS server.

• Restrict NFS exports to the XOA IP address only:
  /srv/nfs/share<XOAIP>/32(rw,sync,no_subtree_check,no_root_squash)

• Do NOT expose the NFS share to the general network or to end-user access.

• Admins who need to edit CSV files can SCP them to/from the XOA:
  EXAMPLE:
  Download CSV from XOA to your workstation
  scp <xoa-user>@<xoa-ip>:/path/to/current-vms.csv ./

  Upload edited CSV back to XOA
  scp ./current-vms.csv <xoa-user>@<xoa-ip>:/path/to/current-vms.csv

• Use firewall rules to enforce NFS access at the network level in addition to the exports configuration

Failure to secure the NFS share is a serious security risk.

---

UPGRADING FROM THE STANDALONE SCRIPT

If you installed the old standalone set-performance.sh script, you can remove it before enabling the plugin as follows:

1. Remove the script:

   sudo rm /usr/local/bin/set-performance.sh
   

2. Remove the crontab entry:

     crontab -e
     (delete the line referencing set-performance.sh)
   

3. Note: The plugin handles its own scheduling via the XO UI. No manual cron configuration is required.

---

INSTALLATION

1. Download the latest airgap release tarball from GitHub:
   https://github.com/johnezero/xo-tag-automation_plugin/releases

2. SCP the tarball to your XOA:

   scp xo-tag-automation-airgap-vX.X.X.tar.gz <xoa-user>@<xoa-ip>:/tmp/
   

3. Create the plugin folder:

   sudo mkdir -p /usr/local/lib/node_modules/xo-server-tag-automation
   

4. Extract directly into the plugin directory:

   sudo tar -xzvf /tmp/xo-tag-automation-airgap-vX.X.X.tar.gz -C /usr/local/lib/node_modules/xo-server-tag-automation/ --strip-components=1
   

5. Restart xo-server:

   sudo systemctl restart xo-server
   

6. Verify registration:

   sudo journalctl -u xo-server -n 100 --no-pager | grep -A3 "tag-automation"
   

   You should see:

   [INFO] xo-tag-automation: Plugin factory called -- xo context: YES
   [INFO] xo-tag-automation: Plugin loaded -- waiting for core started.
   xo:plugin INFO successfully register tag-automation
   

7. Enable and configure the plugin options in XO:
   Settings -> Plugins -> tag-automation -> Enable

---

XO-CLI API METHODS

The plugin exposes several API methods accessible via xo-cli:

xo-cli xo-server-tag-automation.exportCsv
Export current VM inventory to current-vms.csv

xo-cli xo-server-tag-automation.downloadCsvApi
Print CSV content to stdout

xo-cli xo-server-tag-automation.uploadCsvApi content@./current-vms.csv
Push an edited CSV back to the NFS share

xo-cli xo-server-tag-automation.getLog lines=100
View the last N lines of the plugin log

xo-cli xo-server-tag-automation.getDailySummary
View the nightly VM count summary

xo-cli xo-server-tag-automation.getFilePaths
Show all configured file paths

---

LINKS

GitHub: https://github.com/johnezero/xo-tag-automation_plugin
Vates REST API docs: https://xen-orchestra.com/docs/restapi.html

---

STANDARD DISCLAIMER HERE

This software is provided "AS-IS" without any express or implied warranty. While this plugin is being used in a production environment managing live VMs, you should always review the code and test it in a non-production environment before full deployment.
Note: The plugin is designed to ONLY take action on VMs with specific tags assigned (e.g. untagged VMs are never modified).
Use Dry-Run mode to preview all changes (via log file output) before applying them.

Feedback, input and suggestions and always welcome...

@poddingue Thank you!
"Anything and Everything we can to to improve XCP-ng", is the "Name of the Game"

@tjkreidl Yes, it's all good! Happy Day

@tjkreidl Found it. I re-posted the topic back to the hardware category (and linked the pdf's to the #tobiaskreidl github) here:
Server Admin Guide: A Tale of Two Servers: BIOS, GPU, and NUMA Tuning for XCP-ng: Preserving the valuable work done by Tobias Kreidl (@tjkreidl)

WHAT: This post is dedicated to preserving the valuable server administration guide content produced by @tjkreidl, originally titled "A Tale of Two Servers." These articles were first published in 2019 on the Citrix Blogs, which are unfortunately no longer available.

KUDOS: Special thanks to @john.c for performing some incredible web sleuthing to recover this content, and to @tjkreidl for creating these essential guides in the first place — as well as for "Breathing Life" back into them by highlighting their importance before they disappeared forever into the ferocious "Bit-Bucket."

Series Overview & Quick Reference

If you're looking for a high-level summary of the concepts covered in this series — including specific XCP-ng/XO commands for BIOS power management, GPU scheduling, and NUMA inspection — start here:
Quick Reference & Summary Guide

The Complete Series

=========================================

Part 1: How BIOS Settings Can Affect Your Apps and GPU Performance:

A deep dive into CPU Power Management (OS DBPM vs. System DBPM) and Turbo mode.
Read Article

Part 2: GPU Settings and Advanced BIOS Tuning

Exploring Uncore frequency, C1E states, and NVIDIA GPU Scheduler modes (Best Effort vs. Equal Share).
Read Article

Part 3: NUMA, CPUs, Sockets/Cores, and VM Performance

Understanding vNUMA, vCPU oversubscription, and the importance of VM startup order for optimal memory placement.
Read Article

Archived for the XCP-ng community. Questions or additional insights? Please discuss below!

@john.c Will do - and kudos to you on some phenomenal sleuthing work (and to @tjkreidl for sparking ithis contents recall from an early "bit-bucket" grave)! Happy Day All!