From: Bruce Momjian <pgman@candle.pha.pa.us>
Message-Id: <200606040203.k54235c23743@candle.pha.pa.us>
Subject: Re: RES: Initial database loading and IDE x SCSI
In-Reply-To: <4480D427.50207@paradise.net.nz>
To: Mark Kirkwood <markir@paradise.net.nz>
Date: Sat, 3 Jun 2006 22:03:05 -0400 (EDT)
CC: carlosreimer@terra.com.br, Mark Lewis <mark.lewis@mir3.com>,
	Tom Lane <tgl@sss.pgh.pa.us>, pgsql-performance@postgresql.org
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Mark Kirkwood wrote:
> Mark Lewis wrote:
> 
> > 
> > The naive approach works on IDE drives because they don't (usually)
> > honor the request to write the data immediately, so it can fill its
> > write cache up with several megabytes of data and write it out to the
> > disk at its leisure.
> > 
> 
> FWIW - If you are using MacOS X or Windows, then later SATA (in 
> particular, not sure about older IDE) will honor the request to write 
> immediately, even if the disk write cache is enabled.
> 
> I believe that Linux 2.6+ and SATA II will also behave this way (I'm 
> thinking that write barrier support *is* in 2.6 now - however you would 
> be wise to follow up on the Linux kernel list if you want to be sure!)
> 
> In these cases data integrity becomes similar to SCSI - however, unless 
> you buy SATA specifically designed for a server type workload (e.g WD 
> Raptor), then ATA/SATA tend to fail more quickly if used in this way 
> (e.g. 24/7, hot/dusty environment etc).

The definitive guide to servers vs. desktop drives is:

  http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf

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

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