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Old 04-19-2008, 10:46 AM
Bill Moran
 
Posts: n/a
Default Re: Background writer underemphasized ...

In response to Greg Smith <gsmith@gregsmith.com>:

> On Wed, 16 Apr 2008, Bill Moran wrote:
>
> >> bgwriter_delay = 10000ms # 10-10000ms between rounds
> >> bgwriter_lru_maxpages = 1000 # 0-1000 max buffers written/round

> > Have you watched closely under load to ensure that you're not seeing a
> > huge performance hit every 10s when the bgwriter kicks off?

>
> bgwriter_lru_maxpages = 1000 means that any background writer pass can
> write at most 1000 pages = 8MB. Those are buffered writes going into the
> OS cache, which it will write out at its own pace later. That isn't going
> to cause a performance hit when it happens.
>
> That isn't the real mystery though--where's the RAID5 rant I was expecting
> from you?


Oh crap ... he _is_ using RAID-5! I completely missed an opportunity to
rant!

blah blah blah ... RAID-5 == evile, etc ...

--
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/

wmoran@collaborativefusion.com
Phone: 412-422-3463x4023

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