[ale] IDE Raid / Hotswap

[Danny Cox]

Mike,

On Fri, 2003-04-25 at 00:08, Mike Lockhart wrote:
> I need to setup a hotswap raid array for backups at work, and I'm
> thinking of using IDE Raid instead of SCSI due to cost issues.  Does
> anyone know of a good controller card that supports IDE and hotswaping? 
> Additionally, what are some good applications to use for backups?
> (*linux of course*)
> 
> My initial thoughts are somthing like using three 8drive IDE raid cards,
> a dual proc box, and 2 gigs of ram.  I think if I use a board that has 3
> 66MHz pci slots that it should do ok. (Based of google research and this
> link:http://www.tomshardware.com/newsletter/vol3/16/70tb.html).

	Sorry I've taken so long.  My mom-in-law passed away last Sunday, so
the last week has seen very little of me actually reading ALE.

	Nevertheless, I have IDE hot-swap working with Promise and Highpoint
chipsets.  In fact, I think it's pretty generic at this point.  The main
thing to keep in mind is to have ground established when inserting the
drive.  Using rails to do this is usually sufficient.

	If you want the patch for 2.4.20, I'll be happy to send it to you. 
However, it's only one half of the equasion.  The boxes I used had an
ACPI function that would "notice" when a drive was removed or inserted. 
We have a kernel thread polling that memory byte, which upon a change,
would call my routines to handle it.  If you don't need that aspect, and
just want to do things manually, then my patch will work as is.  It
creates a new directory: /proc/sys/dev/hot-swap, with files add, remove,
fake_add, fake_remove, hdd_status, and inject_error.  The first two, add
and remove are the main guys.  When a drive is added, say hda, you
simply "echo 0 >/proc/sys/dev/hot-swap/add", and the drive is registered
with the IDE subsystem.  "echo N >/proc/sys/dev/hot-swap/remove" does
the the opposite.

	Drop me a line if you're interested, of if I'm not explaining things
properly.

-- 
kernel, n.: A part of an operating system that preserves the
medieval traditions of sorcery and black art.

Danny

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