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Date: Tue, 20 Sep 2011 11:01:05 -0500 (CDT)
From: Bob Friesenhahn <bfriesen@simple.dallas.tx.us>
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To: Freddie Cash <fjwcash@gmail.com>
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Cc: freebsd-fs@freebsd.org
Subject: Re: ZFS obn FreeBSD hardware model for 48 or 96 sata3 paths...
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On Mon, 19 Sep 2011, Freddie Cash wrote:
> 
> L2ARC has extreme bandwidth limitations as compared with RAM.  Be careful what you wish for.
> 
> For writes (7 MBps, I believe); there shouldn't be any limits on the reads. 

If (for example) an SSD is used with a 200MB/s read rate for the 
L2ARC, then the L2ARC is limited to 200MB/s (as compared with perhaps 
10GB/s or 20GB/s for RAM).

The L2ARC is really all about eliminating the access latency of 
rotating-rust but any device will provide far less bandwidth than 
system RAM.

Bob
-- 
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
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