Exact error message will be similar to this:

HSCLA24E The migrating partition's virtual SCSI adapter 61 cannot be hosted by the existing virtual I/O server (VIOS) partitions on the destination managed system. To migrate the partition, set up the necessary VIOS hosts on the destination managed system, then try the operation again.

This error message occurs when the LPM validation process can not find the corresponding VSCSI SAN disks on any of the target frames VIO servers.  Check your SAN zoning and masking for the SAN disks is correct and the same for both the source and target frames and VIO servers.

I have seen this error associated with this errors shown in the detailed error output when using EMC storage.

This occurs when you try to LPM from VIOS 2.2.2.2 to VIOS 2.1.3.10-FP23.
The only fix I found so far is to upgrade the target VIOS to 2.2.2.2.

HSCLA356 The RMC command issued to partition vio2 failed. This means that destination VIOS partition vio2 cannot host the virtual adapter 21 on the migrating partition.<br />HSCLA29A The RMC command issued to partition vio2 failed.<br />The partition command is:<br />migmgr -f find_devices -t vscsi -C 0x3 -d 1<br />The RMC return code is:<br />0<br />The OS command return code is:<br />90<br />The OS standard out is:<br />Running method '/usr/lib/methods/mig_vscsi'<br />VIOS_DETAILED_ERROR=Block Device is not compatible with source Attributes , hdiskpower378<br />90