Re: Accessing SCSI-Devices >2TB

Hi all,

thank you for the hints about debugging. 

( I think this should go over to freebsd-scsi_at_. I've archived 
the thread on -current in 
http://rabe.uugrn.org/temp/FreeBSD/bigraid/RAID_2TB.mbox.gz )



I've done some testing.

First was to boot another OS with the RAID in two equal partitions, I
tried with knoppix 3.9 (Linux 2.6.11):
http://rabe.uugrn.org/temp/FreeBSD/bigraid/dmesg.knoppix_partition.txt

... and with the RAID configuread as one big drive:
http://rabe.uugrn.org/temp/FreeBSD/bigraid/dmesg.knoppix_onebig.txt

and here the relevant diffs:
http://rabe.uugrn.org/temp/FreeBSD/bigraid/dmesg.knoppix_diff.txt

Second I rebooted FreeBSD with CAMDEBUG in kernel and enabled it via
"camcontrol debug ..." and did a "camcontrol rescan 1" then:
http://rabe.uugrn.org/temp/FreeBSD/bigraid/freebsd54_camdebug.txt

A complete dmesg.boot of 5.4 can be found under 
http://rabe.uugrn.org/temp/FreeBSD/bigraid/dmesg.freebsd54_onebig.txt

I will have to try a SuSE Linux Live System where this should work
according to the support of the RAID.

The workaround (2 partitions mapped to two LUNs and merged into a RAID
in FreeBSD) might work. I have some days for playing around with the
RAID before I need to set it in production. 

Any idea, whats wrong with it?

Regards
Raphael Becker


On Thu, Jun 09, 2005 at 02:05:11PM +0100, Brian Candler wrote:
> On Thu, Jun 09, 2005 at 11:36:16AM +0200, Raphael H. Becker wrote:
> > The first idea was to have just one large logical drive (LD1) with 12 
> > physical discs (PD1 - PD12), where P1 is HotSpare. The RAID wants to talk 
> > a LBA64 dialect of SCSI AFAIK and FreeBSD isn't able to talk this with 
> > the RAID  --> no /dev/daX!
> 
> SCSI has always used a Linear (or Logical) Block Address offset from the
> start of the disk. What you probably mean is that the controller is issuing
> a READ(16) command instead of a READ(10), for example. See the SCSI
> documentation: e.g.
> http://www.t10.org/ftp/t10/drafts/sbc2/sbc2r16.pdf
> 
> Now, setting aside the ccd workarounds for now, IIUC the fundamental problem
> is that you cannot attach your drive array when it presents itself as a
> single volume with more than 2^31 blocks.
> 
> This means that either:
> (1) there's a problem with your drive array under this condition; or
> (2) there's a problem with your SCSI controller under this condition; or
> (3) there's a problem with FreeBSD under this condition.
> 
> To prove which it is, I think you need to show the actual problematic SCSI
> command sent to the drive, and the actual response (if any) which comes
> back.
> 
> According to your log at
> http://lists.freebsd.org/pipermail/freebsd-current/2005-June/051163.html
> it says that FreeBSD is objecting to the response from the drive array
> (protocol violation in Message In phase)
> 
> Perhaps someone here can say what's the best way to enable this level of
> debugging? From the 5.4 source tree it looks like you can define CAMDEBUG
> when building the kernel, and then use "camcontrol debug" to enable
> debugging for a particular target (or "all")
> 
> Just a suggestion...
> 
> Brian.
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