After migrating from Fixed/Perpetual licensing to Pooled/Flexed license type using LAS based licensing or file-based licensing, Admin Partitions on NetScaler fail to load and may disappear from the running configuration. 

Observed error: 
"ERROR: Cannot allocate memory" 

** This applies exclusively to MPX devices with admin partitions that allocate less bandwidth than the maximum available. For.eg an MPX is using Fixed license and is licensed for 50 Gbps, but has Max Bandwidth of 100 Gbps** 

When using fixed licenses, packet engines are unlocked as per licensed bandwidth.  

This issue is specific to Admin Partitions on NetScaler MPX, where memory is allocated per active packet engine, not globally. 

Key behavior: 

• Each active packet engine reserves memory equal to maxMemLimit  

• Total memory requirement increases with the number of active packet engines  

Formula: 
Total Memory Required = maxMemLimit × Number of Active Packet Engines 

What changes after licensing migration: 

• Fixed Capacity Subscription license → limited active packet engines  

• Pooled/Flexed license → all packet engines become active  

Example: An MPX 16000 can use max 30 Packet Engines with max 128GB of memory.  

For fixed license of 30 GBPS, we unlock 15 PE’s with full 128GB of memory. Customer has configured 10 partitions with a total of 5GB of memory. 

• On Fixed Capacity Subscription license: 5 GB × 15 = 75 GB (within limit)  

• After migration to Pooled/Flexed license: 5 GB × 30 = 150 GB (exceeds 128 GB available)   
  *PE’s have increased to 30 from 15* 

Result:  

• System cannot allocate required memory  

• Admin Partition configuration is skipped during boot  

Steps for Administrator before LAS migration 

Prerequisite: Take a Full Backup of NetScaler before going ahead with any of the below steps. 

 Change in memory allocation for Partitions 

• Option 1:  

• Determine the expected number of active packet engines after migration. Please check: https://docs.netscaler.com/en-us/netscaler-hardware-platforms/mpx/netscaler-hardware-platforms  

• Recalculate memory requirement: 
  maxMemLimit ≤ Available Memory ÷ Number of Active Packet Engines  

• Update configuration by reducing maxMemLimit for Admin Partitions to ensure total memory remains within limits. 

• Option 2: 

• Set the MaxMemLimit value to '0' for all partitions, ensuring partition configurations are not restricted by a memory limit. 

• Following the shift from fixed capacity subscription or perpetual license type to Pooled/Flexed license type (LAS or file based licensing),  
  perform the necessary calculations to reconfigure memory allocation for each partition. (refer to option 1 for calculation information) 

• Establish SNMP alerts and monitor potential memory breaches. 

In case we are unable to accommodate the partitions in available memory, please consider moving some of the partitions to another NetScaler. 

Post-MigrationValidation and Recovery 

• Verify that Admin Partitions are present in the running configuration  

• Check system logs for memory-related errors.  

If partitions are missing: 

1. Restore configuration from backup (ns.conf or saved config)  

1. Modify maxMemLimit values to compliant limits  

1. Reapply the corrected configuration  

1. Save configuration and reboot if required  

Admin Partition missing/fail to load after migrating from NetScaler local license to Pooled/Flexed license