2048kb block size

[Kenneth D. Merry]

On Fri, Oct 07, 2005 at 15:42:04 +0300, Danny Braniss wrote:
> can the da(4) handle non 512 block size? im asking because at 512 all is ok,
> but 2048 does not get past geom. 
> 
> the iSCSI driver has no idea about blocksize, and seems to be doing the right
> thing:
> Oct  5 15:44:45 rnd kernel: da0: 10239MB (5242368 2048 byte sectors: 255H 
> 63S/T 326C)

That looks about right.  The da(4) driver does work with optical disks that
have 2K sectors.  (Or it has in the past.)

> what am i missing? or in other words, is there something i have to do in the
> iscsi driver to fix this?

If you want to eliminate the da(4) driver and GEOM, you can try sending a
read via the pass(4) driver.  This should work:

camcontrol cmd da0 -v -c "28 0 0 0 0 0 0 0 1 0" -i 2048 - > /tmp/da0.sec0

That will read one block from da0, starting at sector 0.

You can increase the number of blocks or read from somewhere else on the
disk as well by changing the CDB around.

That path doesn't go through the da(4) driver or GEOM, so you can eliminate
both of those as possible causes of the problem.

Ken
-- 
Kenneth Merry
ken at FreeBSD.ORG