| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
| Cc: | Greg Smith <greg(at)2ndquadrant(dot)com>, Craig James <craig_james(at)emolecules(dot)com>, Matthew Wakeling <matthew(at)flymine(dot)org>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Weird XFS WAL problem |
| Date: | 2010-06-04 15:18:10 |
| Message-ID: | 201006041518.o54FIA107844@momjian.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
Kevin Grittner wrote:
> Bruce Momjian <bruce(at)momjian(dot)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(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ None of us is going to be here forever. +
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Kevin Grittner | 2010-06-04 15:23:52 | Re: Weird XFS WAL problem |
| Previous Message | Kevin Grittner | 2010-06-04 15:16:41 | Re: Weird XFS WAL problem |