Citrix CVAD
Deep Dive 2026

MCS I/O Optimization (MCSIO) Config

# MCS I/O Optimization — GPO path:
# Citrix > Virtual Desktop Agent > MCS IOO
# Or via Studio Catalog settings

# Key registry (set during VDA install or via GPO):
# HKLM\SOFTWARE\Citrix\MCSIODrv
WriteCacheSize = 256         # MB RAM write cache
WriteCacheDisk = 1024        # MB disk overflow
EnableWriteBackCache = 1     # Required for non-persistent

# Command line: Enable MCSIO at catalog creation
New-BrokerCatalog -Name "Pool1" `
  -MachinesArePhysical $false `
  -MinimumFunctionalLevel L7_20 `
  -ProvisioningType MCS `
  -SessionSupport MultiSession

PVS RAM Cache Sizing Guide

# PVS Write-Back Cache (WBC) — key settings
# PVS Console > vDisk > Properties > Cache

Cache type options:
  1 = Cache on device RAM with overflow to disk  ← Recommended
  2 = Cache on device disk
  3 = Cache on server (avoid — network overhead)
  5 = Cache in device RAM (no overflow — risky)

# RAM cache sizing rule of thumb:
# Task worker: 512 MB–1 GB
# Knowledge worker: 1–2 GB
# Power user: 2–4 GB

# Disk overflow: 10–20 GB per VM on local SSD
# Never put PVS overflow on SAN — defeats purpose

EDT Bandwidth Estimates

HDX Monitor (PowerShell)

# Check active session HDX stats:
# Citrix Director: Monitor > HDX channel data

# PowerShell — session details:
Add-PSSnapin Citrix*
$sessions = Get-BrokerSession -Filter {SessionState -eq 'Active'}
$sessions | Select UserName, Protocol,
  EstablishmentTime, ClientAddress |
  Format-Table -AutoSize

# NetScaler: HDX Insight dashboard
# nscommand: show ica sessions

ICA Proxy Configuration

# NetScaler Gateway ICA Proxy
# Path: Traffic Management > Load Balancing > VS

# Enable ICA proxy on Gateway vServer:
set vpn vserver GATEWAY_VIP -icaOnly OFF
set vpn sessionaction ICA_Proxy `
  -defaultAuthorizationAction ALLOW `
  -transparentInterception OFF `
  -SSO ON `
  -icaProxy ON

# EDT (UDP) for HDX Adaptive Transport:
# Traffic Policy: set ns-profile for EDT
# Ensure UDP 443 open at firewall toward NetScaler

# Verify EDT active (from Director):
# Monitor > Sessions > Protocol column = UDP

StoreFront LB Config (Key Points)

# NetScaler LB for StoreFront HA
# Monitor type: STOREFRONT
add lb monitor SF_Monitor STOREFRONT `
  -storename Store `
  -storefrontaccttype ActiveDirectory

# Service group for SF servers:
add servicegroup SG_SF HTTP
bind servicegroup SG_SF 10.x.x.11 80
bind servicegroup SG_SF 10.x.x.12 80
bind lb vserver SF_VIP SG_SF

# SSL cert binding (wildcard recommended):
bind ssl vserver SF_VIP -certkeyName star.corp.com

# HTTPS redirect:
add responder action redir_https redirect \
  '"https://" + HTTP.REQ.HOSTNAME + HTTP.REQ.URL'
add responder policy redir_http_to_https TRUE redir_https

Check License Status

# Citrix Licensing Manager (web):
# https://[license-server]:8083

# PowerShell:
Get-LicCertificateInfo -AdminAddress https://lic:8083
Get-LicInventory -AdminAddress https://lic:8083

# Check LAS expiry specifically:
# Licenses show "Subscription Advantage Date"
# If date < today: EXPIRED — renew immediately

# Quick check all allocated licenses:
asnp Citrix.*
Get-BrokerController | Select DNSName, State
Get-LicInventory | Select PldName, LicensesInUse, LicensesAvailable

License Server HA

# Citrix License Server — HA best practices:
# No native clustering — use VM HA (vSphere/Hyper-V)
# Take VM snapshots before updates
# Keep license files backed up: 
#   C:\Program Files\Citrix\Licensing\MyFiles\

# DDC license server redundancy:
# Configure 2+ license servers in Studio
# Studio > Settings > Licensing > Server list

# License grace period: 30 days if license server
# unreachable. After grace: new sessions rejected.
# Plan: snapshot restore < 15 min RTO for license server