Apple Server Diagnostics - Manual (Page 46)

46 Appendix Server Diagnostics Test Reference
Even though simple memory tests don’t test all memory, you can run these tests to
detect intermittent memory issues.
In Server Diagnostics EFI, all memory tests (simple, multicore, and extended) are
grouped under Memory tests.
Note: The time required to complete memory tests correlates to the amount of
memory being tested. These estimates are based on testing 2 GB of memory.
Test Estimated completion time Description
Address as Data 5 seconds Tests memory using the
memory address as data.
Patterns 10 seconds Tests memory using different
data patterns.
Marching Ones and Zeros 10 seconds Tests memory by walking 1s and
0s up and down memory.
Knaizuk Hartmann 5 seconds Tests memory using this
algorithm.
MOD3 15 seconds Tests memory using this
algorithm.
March U 1 minute Tests memory using Van de
Goor’s March U algorithm.
Random 15 seconds Uses pseudo-random values.
Block Checkerboard 32 5 seconds Alternates 32-bit words with all
1s and all 0s, and then with all
0s and all 1s.
Bit Checkerboard 32 5 seconds Alternates bits with all 1s and
all 0s, and then with all 0s and
all 1s.
Sequential Byte Block 32 9 minutes Fills all bytes sequentially with
patterns starting at 0x00 and
ending at 0xFF.
Walking One 32 5 minutes Walks 1s up and down memory.
Walking Zero 32 5 minutes Walks 0s up and down memory.
Walking Spread Bit 32 5 minutes Walks 0b01 up and then walks
0b10 down memory.
Walking Bit Flip 32 5 minutes Alternates words with walking
1 and walking 0, and then
alternates with walking 0 and
walking 1.