Re: [PERFORM] Arguments Pro/Contra Software Raid - Mailing list pgsql-general

From Bruce Momjian
Subject Re: [PERFORM] Arguments Pro/Contra Software Raid
Date
Msg-id 200605100102.k4A12wa12853@candle.pha.pa.us
Whole thread Raw
In response to Re: [PERFORM] Arguments Pro/Contra Software Raid  (Scott Marlowe <smarlowe@g2switchworks.com>)
Responses Re: [PERFORM] Arguments Pro/Contra Software Raid
List pgsql-general
Scott Marlowe wrote:
> Actually, in the case of the Escalades at least, the answer is yes.
> Last year (maybe a bit more) someone was testing an IDE escalade
> controller with drives that were known to lie, and it passed the power
> plug pull test repeatedly.  Apparently, the escalades tell the drives to
> turn off their cache.  While most all IDEs and a fair number of SATA
> drives lie about cache fsyncing, they all seem to turn off the cache
> when you ask.
>
> And, since a hardware RAID controller with bbu cache has its own cache,
> it's not like it really needs the one on the drives anyway.

You do if the controller thinks the data is already on the drives and
removes it from its cache.

--
  Bruce Momjian   http://candle.pha.pa.us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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