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From: NeilBrown <neilb@suse.de>
To: "Alexander Kühn" <alexander.kuehn@nagilum.de>
Cc: Wakko Warner <wakko@animx.eu.org>, linux-raid@vger.kernel.org
Subject: Re: Thought about delayed sync
Date: Mon, 10 Oct 2011 09:12:36 +1100	[thread overview]
Message-ID: <20111010091236.5bcbacd8@notabene.brown> (raw)
In-Reply-To: <20111009133216.Horde.3I8nXJk8pphOkYZAj4hRFEg@cakebox.homeunix.net>

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On Sun, 09 Oct 2011 13:32:16 +0200 Alexander Kühn
<alexander.kuehn@nagilum.de> wrote:

> 
> Zitat von NeilBrown <neilb@suse.de>:
> 
> >  http://neil.brown.name/blog/20110216044002#5
> 
> Using one bit per stripe looks like the natural choice to me, no?

It might seem natural, but that doesn't mean it is good.

My rule-of-thumb is that each bit should correspond to about one second of
resync time.  So that is probably 50-100MB these days.
So a 4TB drive would have 40,000-80,000 bits or be 5KB to 10KB in size.
I would probably rather a 4KB bitmap, so each bit could correspond to 2-3
seconds which is probably fine.
That might line up with the stripe size, or it might not.  And whether is
does or not is largely irrelevant to the code.

NeilBrown

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  reply	other threads:[~2011-10-09 22:12 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-08 18:03 Thought about delayed sync Wakko Warner
2011-10-08 22:00 ` Thomas Fjellstrom
2011-10-09 12:04   ` Wakko Warner
2011-10-09 12:34     ` Thomas Fjellstrom
2011-10-09 13:44       ` Wakko Warner
2011-10-08 22:36 ` NeilBrown
2011-10-09 11:32   ` Alexander Kühn
2011-10-09 22:12     ` NeilBrown [this message]
2011-10-09 11:56   ` Wakko Warner

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