Re: Schrödinger's hash

On 6/1/26 14:15, Charles Curley wrote:
> Some additional testing.
> 
> Suspecting a bad hard drive, I ran more extended tests on all four
> members of the RAID array. One showed problems:
> 
>        "Error 1 [0] occurred at disk power-on lifetime: 6777 hours (282 days + 9 hours)",
>        "  When the command that caused the error occurred, the device was active or idle.",
>        "",
>        "  After command completion occurred, registers were:",
>        "  ER -- ST COUNT  LBA_48  LH LM LL DV DC",
>        "  -- -- -- == -- == == == -- -- -- -- --",
>        "  40 -- 51 00 01 00 00 00 00 00 00 40 00  Error: UNC 1 sectors at LBA = 0x00000000 = 0",
>        "",
>        "  Commands leading to the command that caused the error were:",
>        "  CR FEATR COUNT  LBA_48  LH LM LL DV DC  Powered_Up_Time  Command/Feature_Name",
>        "  -- == -- == -- == == == -- -- -- -- --  ---------------  --------------------",
>        "  25 00 00 00 01 00 00 00 00 00 00 40 00     00:08:36.585  READ DMA EXT",
>        "  ec 00 00 00 00 00 00 00 00 00 00 00 00     00:08:31.545  IDENTIFY DEVICE",
>        "  b0 00 da 00 00 00 00 00 c2 4f 00 00 00     00:08:31.542  SMART RETURN STATUS",
>        "  b0 00 d2 00 f1 00 00 00 c2 4f 00 00 00     00:08:31.541  SMART ENABLE/DISABLE ATTRIBUTE AUTOSAVE",
>        "  ec 00 00 00 00 00 00 00 00 00 00 00 00     00:08:31.541  IDENTIFY DEVICE",
>        "",
>        "SMART Extended Self-test Log Version: 1 (1 sectors)",
>        "Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error",
>        "# 1  Extended offline    Completed without error       00%      6756         -",
>        "# 2  Extended offline    Completed without error       00%      6573         -",
>        "# 3  Extended offline    Completed without error       00%       102         -",
>        "# 4  Short offline       Completed without error       00%        96         -",
>        "",
> 
> 
> So I did the obvious: I failed and remove the drive from the array. The
> problem still showed up, but not as many fails in the same data set.
> 
> I have since added the drive back to the array, and am testing the
> array now.
> 
> mdadm --monitor --test --oneshot /dev/md0
> 
> I begin to wonder if I have a bad motherboard.


Up until 2019, I was using Debian GNU/Linux on desktop hardware as a 
file server.  When I upgraded to a server motherboard and ECC memory, I 
started seeing DMA errors.  During trouble-shooting, I realized that I 
had been collecting SATA parts since the days of SATA I 150 Gbps -- 
HBA's, cables, racks, and drawers.  My file server had a mix of various 
known and unknown parts, including red SATA cables (red dye can cause 
copper conductors to oxidize into dust).  So, I replaced all of the 
unknown and obsolete parts with new parts clearly rated and marked for 
SATA III 6 Gbps.  The disk problems went away.  When I wanted more 
HDD's, I bought SAS 6 Gbps HBA's, cables, and HDD's.


Similarly, most of the memory problems I encountered were caused by 
incompatibility between the motherboard and the memory module(s).  I 
suggest documenting your motherboard, documenting your memory modules, 
and doing the homework.  Memory manufacturers typically have a search 
feature on their web site that will produce a list of compatible memory 
modules given a computer or motherboard make and model.  eBay sellers 
often include the computer/motherboard make/model for pulled memory 
modules.  And, you can always STFW.


For a server, I prefer and recommended workstation/server motherboards, 
ECC memory, ext4/UFS for the system disk, and ZFS RAID10 for data.


David