sbw@naucse.UUCP (Steve Wampler) (08/29/89)
Sigh. I had forgotten that iv cann't be used to change the VHB
on a drive with >1024 cylinders. Is there another (easy) way
to change the step-rate on such a drive? Will the extended
diagnostics let me do it without munging the existing file
system?
I suppose I could open /dev/rfp010 and read in the VHB myself,
but I don't have a layout of the VHB. (Since the step-rate
change only takes effect on reboots, this would work, wouldn't it?)
--
Steve Wampler
{....!arizona!naucse!sbw}lenny@icus.islp.ny.us (Lenny Tropiano) (08/29/89)
In article <1666@naucse.UUCP> sbw@naucse.UUCP (Steve Wampler) writes: |>Sigh. I had forgotten that iv cann't be used to change the VHB |>on a drive with >1024 cylinders. Is there another (easy) way |>to change the step-rate on such a drive? Will the extended |>diagnostics let me do it without munging the existing file |>system? |> ... I made a program that would patch iv(1M) to allow >1024 cylinders. It was posted to unix-pc.sources a while back, if you never received it, let me know. Of course IT'S UNTESTED. I don't think it would hurt your disk, but I couldn't guarantee. Backups are of course suggested. |>I suppose I could open /dev/rfp010 and read in the VHB myself, |>but I don't have a layout of the VHB. (Since the step-rate |>change only takes effect on reboots, this would work, wouldn't it?) The layout for the VHB is in /usr/include/sys/gdisk.h: /* volume home block on disk */ struct vhbd { uint magic; /* S4 disk format code */ int chksum; /* adjustment so that the 32 bit sum starting from magic for 512 bytes sums to -1 */ struct gdswprt dsk; /* specific description of this disk */ ... You could write a program that opened up /dev/rfp010, read in struct vhbd and then change vhb.dsk.step = 14 and write it back out (basically what iv(1M) does...) Hope this helps, Lenny -- Lenny Tropiano ICUS Software Systems [w] +1 (516) 589-7930 lenny@icus.islp.ny.us Telex; 154232428 ICUS [h] +1 (516) 968-8576 {ames,pacbell,decuac,hombre,talcott,sbcs}!icus!lenny attmail!icus!lenny ICUS Software Systems -- PO Box 1; Islip Terrace, NY 11752
jcm@mtunb.ATT.COM (was-John McMillan) (09/01/89)
In article <950@icus.islp.ny.us> lenny@icus.islp.ny.us (Lenny Tropiano) writes: : >You could write a program that opened up /dev/rfp010, read in struct vhbd >and then change vhb.dsk.step = 14 and write it back out (basically what >iv(1M) does...) : For your own peace of disk, understand and maintain the required check sums if you are going to re-write critical disk blocks. As I recall... The VHB is checksum'd to -1; The bad block list is likewise checksum'd. john mcmillan -- att!mtunb!jcm