We have seen a problem with copying a large volume between machines and the resulting volume having a different checksum than the source volume. We found a bad DIMM on the target machine using memtest, but we now have questions that need answers for our users. Since the memory controller is built in to the Opteron, and the Opteron uses ECC memory, is the ECC correction done at the hardware level via the memory controller ? Is this dependent on the motherboard chipset, or are the options the same regardless of chipset due to the controller being built onto the processor ? I seem to remember seeing some messages about whether or not to turn on background scrubbing on the ECC system at the BIOS level. Are there problems with the Linux kernel doing this, or is just a memory latency issue due to overhead ? If the hardware controller cannot correct the error, does it raise an exception to the OS ? If so, does the Linux kernel catch the signal ? Log the error, or crash the system ? Is this configurable ? We have a mix of the UnitedLinux kernel 2.4.19-smp, SuSE 9.0 2.4.21-193-smp, and the 2.4.22 kernel from kernel.org. Do these kernels need to be ECC aware to catch sny signals, and if so, are they ? Thanks for any help..... Kevin Kevin Gassiot Advanced Systems Group Visualization Systems Support Veritas DGC 10300 Town Park Dr. Houston, Texas 77072 832-351-8978 kevin_gassiot@veritasdgc.com