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Message-Id: <200803170116.19546.phillips@phunq.net>
Date: Mon, 17 Mar 2008 00:16:18 -0800
From: Daniel Phillips <phillips@...nq.net>
To: david@...g.hm
Cc: David Newall <davidn@...idnewall.com>,
Alan Cox <alan@...rguk.ukuu.org.uk>, Willy Tarreau <w@....eu>,
linux-kernel@...r.kernel.org
Subject: Re: [ANNOUNCE] Ramback: faster than a speeding bullet
On Sunday 16 March 2008 23:49, david@...g.hm wrote:
> > Mirroring on the other hand, makes a realtime copy of a volume, that is
> > never out of date.
>
> so just mirror to a local disk array then.
Great idea. Except that the disk array has millisecond level latency,
when what we trying to achieve is microsecond level latency.
> a local disk array has more write bandwidth than a network connection to a
> remote machine, so if you can mirror to a remote machine you can mirror to
> a local disk array.
So you could potentially connect to a _huge_ disk array and write deltas
to it. The disk array would have to support roughly 3 Gbytes/second of
write bandwidth to keep up with the Violin ramdisk. Doable, but you are
now in the serious heavy iron zone.
Personally, I like my nice simple design a lot more. Just mirror it, as
many times as you need to satisfy your paranoia. Or how about go write
your own?
Daniel
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