Re: Weird XFS WAL problem

Kevin Grittner wrote:
> Bruce Momjian <bruce@momjian.us> wrote:
>
> > On another topic, I am a little unclear on how things behave when
> > the drive is write-back. If the RAID controller card writes to the
> > drive, but the data isn't on the platers, how does it know when it
> > can discard that information from the BBU RAID cache?
>
> The controller waits for the drive to tell it that it has made it to
> the platter before it discards it.  What made you think otherwise?

Because a write-back drive cache says it is on the drive before it hits
the platters, which I think is the default for SATA drive.  Is that
inaccurate?

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + None of us is going to be here forever. +