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Date: Wed, 08 Dec 2004 17:46:38 -0600
From: Brian King <brking@us.ibm.com>
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To: "Bagalkote, Sreenivas" <sreenib@lsil.com>
CC: Matt Domsch <Matt_Domsch@dell.com>,
       "'James Bottomley'" <James.Bottomley@SteelEye.com>,
       "'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>,
       "'linux-scsi@vger.kernel.org'" <linux-scsi@vger.kernel.org>,
       "'bunk@fs.tum.de'" <bunk@fs.tum.de>, "'Andrew Morton'" <akpm@osdl.org>,
       "Ju, Seokmann" <sju@lsil.com>, "Doelfel, Hardy" <hdoelfel@lsil.com>,
       "Mukker, Atul" <Atulm@lsil.com>
Subject: Re: How to add/drop SCSI drives from within the driver?
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Bagalkote, Sreenivas wrote:
> Adding a drive:- For application to use sysfs to scan newly added drive,
> it needs to know the HCTL (SCSI address - Host, Channel, Target & Lun)
> of the drive. Driver is the only one that knows the mapping between a 
> drive and the corresponding HCTL.

Can you explain from a high level how megaraid adds logical devices?
I assume a management app of some sort sends a command to the adapter
to create a disk array. What interface is used for this?
Does this trigger any notification from the adapter to the device
driver?

> Removing a drive:- There is no sane way for the application to map out
> drives to /dev/sd<x>. 

This information is all available in sysfs. Have you looked at libsysfs
at all?



-- 
Brian King
eServer Storage I/O
IBM Linux Technology Center