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Re: write cache on 3ware controller and XFS -- 3Ware uses SRAM (battery

To: Seth Mos <knuffie@xxxxxxxxx>
Subject: Re: write cache on 3ware controller and XFS -- 3Ware uses SRAM (battery not required?)
From: "Bryan J. Smith" <b.j.smith@xxxxxxxx>
Date: Tue, 05 Nov 2002 16:26:41 -0500 (EST)
Cc: Christophe Zwecker <doc@xxxxxxxxxx>, linux-xfs@xxxxxxxxxxx
In-reply-to: <4.3.2.7.2.20021105215943.03941310@pop.xs4all.nl>
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Quoting Seth Mos <knuffie@xxxxxxxxx>:
> The 3ware controller should easily beat the 3MB/s mark though.
> What disks are attached, what speed and size, how many, what sort of
> raid config. Does it have a battery cache.

Unfortunately, 3Ware cards don't have a battery cache.  I find this a stupid
design decision because 3Ware cards use SRAM, instead of DRAM, which means you
only need a fraction of the juice to maintain the data.

Unless, of course, they _are_ using capacitors to provide the small amount of
power to maintain the data in a SRAM between reboots and short power outtages. 
SRAM (combinational boolean) requires only a very small amount of power compared
to DRAM (leaky cell) .

Someone should ping 3Ware on this design question.

-- 
Bryan J. Smith, E.I.            Contact Info:  http://thebs.org
A+/i-Net+/Linux+/Network+/Server+ CCNA CIWA CNA SCSA/SCWSE/SCNA
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'In the new commercials for MSN 8, a guy dressed in a Microsoft
 Butterfly costume drops out of a "cocoon" ... nobody at
 Microsoft ... knows that a butterfly doesn't emerge from a
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 should not be all that surprising since Microsoft seems to
 have problems recognizing bugs ..."' -- Cringely



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