Migrating from adaptec 39320 to lsi u320-2

[Scott Long]

Nico -telmich- Schottelius wrote:
> 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?

There are no tools for shrinking UFS that I know of.  Moving the gmirror
metadata would require that it be regenerated with a new calculated disk
size.  You could probably dump the contents of each filesystem to tape,
recreate your arrays and mirrors from scratch, and then restore the
dump.

Scott