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Date:      Mon, 24 Nov 1997 21:13:31 -0800 (PST)
From:      Simon Shapiro <shimon@simon-shapiro.org>
To:        Ricardo Kleemann <ricardo@americasnet.com>
Cc:        freebsd-scsi@freebsd.org, "N.Del More" <noel@inr.net>
Subject:   Re: DPT PM2144UWR
Message-ID:  <XFMail.971124211331.shimon@Simon-Shapiro.ORG>
In-Reply-To: <Pine.LNX.3.95.971120180436.12632B-100000@linux1.americasnet.com>

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On 21-Nov-97 Ricardo Kleemann wrote:
> Hi,
> 
> That sounds wonderful. Couple of questions:
> 
> 1. If there IS a freebsd driver, where would I find it?

ftp://simon-shapiro.org/crash. Boot floppies in /FreeBSD

> 2. Can you explain to me how the RAID 5 works on the DPT? For
> example, how
> is recovery done upon failure of one of the drives?

I'll stick to the example... :-)
One of three ways:

a.  On the DEC StorageWorks cabinet (DPT 9W, etc), the dead drive blinks
    yellow.  You pull it out and put a new one.

b.  Shutdown the machine, unplug the bad drive, plug in a new, same or
    larger capacity drive, boot and wait for the drive lights to stop
    glowing.

c.  Boot DOS, start DPTMGR, click the mouse on the array.  Click on
    REBUILD.

I could tech you how to recover from total failure (more than one drive
in the array failing) too, but DPT support likes to have this trick up
THEIR sleeve :-)

If you have money/space, you can leave a drive ``unused'' in the disk
bay and tell DPT to use it as a ``Hot Spare''.  It will then go to
service automatically, with no shutdown even on non-hot cabinets.

You can have multiple hot Spares, but they do not cross controller
boundries.

> 3. In RAID 5 mode, how does the diskspace work out? What I mean is
> how do
> you calculate it?

(N-1)  5 drives give you useful sorage equal to 4/5 the total
capacity.

It's easy for RAID 0 (add the drives), RAID 1 is
> the
> total divided by the number of mirrors.

RAID-1 is 2*N where N is disk capacity.  RAID-1 is only two drives.

But
in RAID 5 what's the
> calculation? If I use 3 2.5Gb drives, how much total space would I
> have?

See above.

> 
> thanks
> Ricardo
> 
> On Thu, 20 Nov 1997, N. Del More wrote:
> 
>> I've been told that their is a driver available for it, frankly, I
>> HOPE
>> that the FreeBSD org begins supporting the DPT cards since it works
>> the
>> absolute NUTS under BSDI!!
>> 
>> Not only that, but it's almost "sexy" to watch in action!!  All them
>> neat
>> LED's on the card blinkin' and flashin' (woohoo!!).
>> 
>> Seriously though, it dropped right into the BSDI server, and came up
>> screaming with a couple of Barracuda's attached.  Not only that but
>> it
>> concurrently supports SCSI/SCSI-2 (8 bit) on a separate channel, has
>> the
>> RAID add-on card. and up to 64 MB of cache.
>> 
>> Finally, the Adaptec 2940 that resided in the box beforehand,
>> couldn't even
>> handle patching the kernel without doing each patch one at a time to
>> avoid
>> a kernel panic and shutdown.  The DPT flew through it, and on a
>> Pentium 233
>> with 128 Mb. RAM applied all of the 3.0 -> 3.1 BSDI patches in 1
>> min., 3
>> sec.  A fellow ISP who was helping me with the upgrade suggested I
>> might
>> not get out of his house with it.
>> 
>> I've used Adaptec for years, but now I'm hooked on DPT!!
>> 
>> Noel
>> 
>> At 10:30 AM 11/20/97 -0800, you wrote:
>> >can anyone confirm freebsd supports the DPT raid controller
>> >(2144UWR)?
>> 
>> 
>> 
>> +------------------------------+  
>> +---------------------------------+
>> | N.B. Del More  noel@inr.net   \   \  An Internet Connection? 
>> | Sure!|
>> | inr.NET                        \   \  Do you want to be on        
>> | |
>> | InterNet Resource Networks, LLC \   \   diss.net ?                
>> | |
>> |  http://www.inr.net              \   \   datt.net ?               
>> |  |
>> |  http://www.diss.net              \   \   or do you just wanna be 
>> |  |
>> |  http://www.datt.net               \   \   on da inr.net ?        
>> |  |
>> +-------------------------------------+  
>> +--------------------------+
>> 
> 


If Microsoft Built Cars:

There would be an "Engine Pro" with bigger turbos, but it would be
slower on most existing roads.


Sincerely Yours, 

Simon Shapiro
Shimon@Simon-Shapiro.ORG                      Voice:   503.799.2313



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