Migrating from adaptec 39320 to lsi u320-2

[Nico -telmich- Schottelius]

Scott Long [Wed, Jun 13, 2007 at 01:46:37AM -0600]:
> Nico -telmich- Schottelius wrote:
> > Hello guys!
> > 
> > I replaced the 39320 in our dell sc1425 with a lsi logic u320-2.
> 
> This is a MegaRAID controller, yes?

Yes

> > [...]
> 
> It sounds like you've purchased a RAID controller, not a SCSI
> controller.  I know that statement sounds foolish.  However, a RAID
> controller is not meant to provide direct, raw access of the disk to
> the OS, it's meant to provide access to storage volumes that are backed
> by disks.  The controller is going put management/configuration metadata
> onto certain sectors of the disk, and it's going to hide those sectors
> from the OS.  That's simply how it works.

Ok, I thought one could use the raid controller in 'dumb' mode: like
creating two raid0 arrays with one member.
And then using those two arrays under freebsd to bind them with gmirror.

Don't you think that it is possible to shrink the filesystem on the
disks, move the gmirror data some bytes to the front and then have spare
bytes for the size the lsi uses for metadata?

> You have two options:
> 
> 1.  Give up on using gmirror and use the hardware raid capabilities of
> the controller that you purchased.

Is not my favourite option, but perhaps the next best option we've here.

> 2.  Return your RAID controller and purchase a SCSI controller.

The problem is that we are a bit under pressure here, as the second
sc1425 is already running in productive mode and "freezes" (as described
in previous posts) about once a week.

Nico

-- 
Think about Free and Open Source Software (FOSS).
http://nico.schottelius.org/documentations/foss/the-term-foss/

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