Supermicro Optane Persistent Memory 200 Series User Manual page 9

Chapter 1: Introduction
that is immune to single-bit errors so that the data that is read from each word is always
the same as the data that had been written to it. ECC memory will protect against any
additional memory failure caused by a 'single-bit' error in the same memory rank.
SDDC
SDDC (Single Device Data Correction) checks and corrects single-bit or multiple-bit (4-bit
max.) memory corruptions and errors that affect an entire single x4 DRAM device. SDDC
Plus One is the enhanced feature to SDDC. Using this enhanced feature will spare the
faulty DRAM device out after an SDDC event has occurred. After the event, ECC mode will
be activated to further protect the system against any additional memory failure caused by
a 'single-bit' error in the same memory rank.
DDDC
DDDC (Double Device Data Correction) provides memory-error checking and correction and
it also prevents the system from issuing a performance penalty before a device fails. Please
note that virtual lockstep mode might be affected until a faulty DRAM module is spared.
Patrol scrubbing
Patrol Scrubbing is a process that allows the CPU to correct correctable memory errors
detected on a memory module and send the correction to the requestor (the original source).
When Patrol Scrubbing is activated, the IO hub will read and write back one cache line
every 16K cycles if there is no delay caused by internal processing. By using this method,
roughly 64 GB of memory behind the IO hub will be scrubbed every day.
Demand scrubbing
Demand Scrubbing is a process that allows the CPU to correct correctable memory errors
found on a memory module. When the CPU or I/O issues a demand-read command, and the
read data from memory turns out to be a correctable error, the error is corrected and sent
to the requestor (the original source). In the meantime, system memory is updated as well.
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