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Date: Tue, 15 Oct 2002 13:54:02 -0700
From: Greg KH <greg@kroah.com>
To: Steven Dake <sdake@mvista.com>
Cc: Michael Clark <michael@metaparadigm.com>, linux-kernel@vger.kernel.org
Subject: Re: [ANNOUNCE] [PATCHES] Advanced TCA Hotswap Support in Linux Kernel
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References: <3DAB1007.6040400@mvista.com> <20021015052916.GA11190@kroah.com> <3DAC52A7.907@mvista.com> <3DAC685B.9070102@metaparadigm.com> <3DAC6C7B.1080205@mvista.com> <20021015203423.GI15864@kroah.com> <3DAC7EAA.5020408@mvista.com>
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On Tue, Oct 15, 2002 at 01:46:34PM -0700, Steven Dake wrote:
> The data/telecoms I've talked to require disk hotswap times of less then 
> 20 msec from notification of hotwap to blue led (a light used to 
> indicate the device can be removed).  They would like 10 msec if it 
> could be done.  This is because of how long it takes on a surprise 
> extraction for the hardware to send the signal vs the user to disconnect 
> the hardware.

But what starts the "notification of hotswap"?  Is this driven by the
user somehow, or is it a hardware event that happens out of the blue?

> For legacy systems such as SAFTE hotswap, polling through sg at 10 msec 
> intervals would be extremely painful because of all the context 
> switches.  A timer scheduled every 10 msec to send out a SCSI message 
> and handle a response if there is a hotswap event is a much better course.

What generates the hotswap event?

thanks,

greg k-h
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