From mboxrd@z Thu Jan  1 00:00:00 1970
From: Bill Davidsen <davidsen@tmr.com>
Subject: Re: Write-intent bitmap decreases or increase performance of RAID5?
Date: Sun, 04 Jul 2010 20:14:21 -0400
Message-ID: <4C3123DD.9090509@tmr.com>
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To: "Majed B." <majedb@gmail.com>
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Majed B. wrote:
> How much RAM does your machine have?
>
> Write to the disk an amount that is larger than the amount of RAM and
> see if you get the same result.
>
> Also you can use hdparm to flush the caches before running dd the 2nd time.
>   

See the meaning of the fdatasync option to dd and the 
/proc/sys/vm/drop_cache control. You are right about hdparm, but it only 
matters if you are using tiny data, drive caches are small.

-- 
Bill Davidsen <davidsen@tmr.com>
  "We can't solve today's problems by using the same thinking we
   used in creating them." - Einstein