scsi problem on a scorpio (715)

[Damien <Damien@cetic.be>]

Now that my 712 runs happily (Thanks again), I'm giving a 
chance to my 715 (no more parisc systems after that :-) ).

(This post is a kind of follow up to a thread I have seen on 
the parisc-linux archive. Feel free to comment where/how I 
should post)


It has 2 disks (Quantum 525 MB & Seagate 525 MB) and the 
installation crashes, while formating, if I try to install 
on both drives, or try to do something with the Quantum drive.
Debian is installed on the Seagate drive and I would like to 
use both drives.


"Reduce Tag queue depth or disable Write Cache"...  Hum, so 
my problem has a name and a solution. OK, so:


How do I disable write cache?

I downloaded scsitools and sg3-utils, I can see that write 
cache is enabled (sg -a /dev/sdx). How do I disable that?
(By the way, disabling write cache is better for 
"correctness", but I read somewhere that it may reduce the 
(somewhat long now) drive life).


How do I reduce "Tag queue depth", i.e. recompile the 53c700 
driver?
Do I have to:
- download kernel sources
- change #define NCR_700_MAX_TAGS in drivers/scsi/53c700.h
- then "simply" (well, I never did that) recompile and 
install the new kernel?


Thanks for your help.


--
Damien