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Date:      Wed, 18 Jun 2003 15:44:14 -0500
From:      Eric Anderson <anderson@centtech.com>
To:        "Jin Guojun [DSD]" <j_guojun@lbl.gov>
Cc:        freebsd-performance@freebsd.org
Subject:   Re: freebsd-performance Digest, Vol 4, Issue 7
Message-ID:  <3EF0CF1E.9020901@centtech.com>
References:  <20030614190033.7F0DE37B407@hub.freebsd.org> <20030615091254.M85497@bluhayz.org> <3EF0B507.2B1B6FDF@lbl.gov> <3EF0C5FA.302@centtech.com> <3EF0CADD.B096A242@lbl.gov>

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Jin Guojun [DSD] wrote:
> Eric Anderson wrote:
> 
> 
>>>Very minimum.
>>>It was slow on SCSI bus , but I do not have time to diagnose,
>>>which can be very time consuming.
>>
>>My tests have shown that a GOOD hardware RAID5 controller can really
>>help you out when it's being slammed (specially over NFS) - I use Dell
>>PERC/2 and PERC/3 controllers (rebranded AMI RAID boards).  They run
>>like champs, and I get 40MB/s sustained xfers..
> 
> 
> What did you mean sustained xfers ? -- in and out, or just read out.

sustained writes (not burst transfers) and sustained reads.. With 
hardware RAID's that have cache memory on them (as the PERC's do - mine 
has 128mb), you can get huge burst speeds (all in memory, so it makes 
sense).  If you have a machine that is writing small files constantly, 
the cache can significantly help.  However, putting a lot of extra 
memory in the server running a software RAID can do this with similar 
results.  I always suggest piling on the RAM for servers..

Eric


-- 
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Eric Anderson	   Systems Administrator      Centaur Technology
Attitudes are contagious, is yours worth catching?
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