drive selection for disk arrays

David Christensen dpchrist at
Mon Mar 30 08:09:55 UTC 2020

On 2020-03-27 18:46, David Christensen wrote:
> On 2020-03-27 17:45, Karl Denninger wrote:
>> On 3/27/2020 19:39, David Christensen wrote:
>>> On 2020-03-27 02:45, Polytropon wrote:
>>>> When a drive _reports_ bad sectors, at least in the past
>>>> it was an indication that it already _has_ lots of them.
>>>> The drive's firmware will remap bad sectors to spare
>>>> sectors, so "no error" so far.
>>> If a drive detects an error, my guess is that it will report the error
>>> to the OS; regardless of the outcome of a particular I/O operation
>>> (data read, data written, data lost) or internal actions taken (block
>>> marked bad, block remapped, etc.).  It is then up to the OS to decide
>>> what to do next.  RAID and/or ZFS offer the means for shielding the
>>> application from I/O and drive failures.
>> Yes, but...
>> Those drives that can do "SMART" will report (if you have a patrol
>> daemon for it running) if they do a "silent" sector reassignment.
>> Otherwise the OS is none the wiser and neither is ZFS (or anything
>> else.) 
> I guess I need to RTFM:

That specification seems to address the HBA.  It references the Serial 
ATA Revision 2.6 specification, which has been superseded.

"SATA-IO" (consortium?) seems to control SATA specifications.  "Serial 
ATA Revision 3.3 Specification (released February 2016)" is recommended 
for current implementations.  It might contain the answers to our 
questions, but purchase is required:


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