Vinum Offset for Swap: 265 or 281?

[rtjohan at syspres.com]

So, my understanding of the bsdlabel process seemed correct:
  1) modify swap partition size to be 281 less than what sysinstall 
created the partition as
  2) have the swap offset at 281 instead of 0
  3) add vinum partition set to the size of "c" minus 16
  4) have vinum partition offset at 16

I might have misunderstood the vinum subdisks settings in the vinum 
configuration file though. I thought the process was:
  1) Each vinum subdisks uses the size of the partition it will be 
taking over from
   2) The subdisk offset is = (partition offset - 16)

Should the subdisk offset be equal to the partition offset?

Again, this is in respect to FreeBSD 5.1 RELEASE with mirrored vinum 
boot disks.

Are there known major bugs related to the 5.1 RELEASE as well?

Thanks for your help,
Richard

Greg 'groggy' Lehey wrote:

>On Sunday, 19 October 2003 at  0:42:38 -0700, rtjohan at syspres.com wrote:
>  
>
>>Hi,
>>
>>Sanity check whether the mirrored vinum root drive is setup correctly.
>>Going to setup two more machines the same way, so wanted to make sure the
>>reference machine was setup correctly.
>>
>>Was surprised to see that the vinum dumpconfig shows the offset for the
>>swap partition to be 265. Remember vaguely that it was supposed to be 281.
>>Do I have a misconfigured machine? The bsdlabel reports the offset to be
>>281. The vinum.conf used driveoffset of 265s for swap - would think it
>>should have been 281s.
>>
>>The machine works, but have had a couple of unexplained reboots. The
>>mirrored drives are ad4s1 and ad8s1.
>>    
>>
>
>Vinum uses the first 265 sectors on a drive for configuration
>information.  That has never changed.  It leaves the first 7 sectors
>free for other stuff and puts the Vinum label in sector 8.
>Unfortunately, this isn't compatible with bootstraps, which use
>sectors 1 to 16.  The result is that if you put a Vinum drive exactly
>at the beginning of a bootable disk, you will overwrite the bootstrap.
>Thus the recommendation to put the drive at offset 16, so that nothing
>will get clobbered.  This means that the first subdisk in the drive
>will be at offset 281 from the beginning of the disk.  The offset of
>the first subdisk in the drive remains the same at 265.  That's what
>you have on your system:
>  
>
>> b:   4194023      281      swap
>> h: 398283401       16     vinum
>>    
>>
>
>If you're having "reboots" (I suppose you mean panics or spontaneous
>resets), it's almost certainly not because of the disk layout.  Follow
>the instructions and we can probably find out what it is.  Note that
>Vinum seems to be tickling bugs in -CURRENT ata code at the moment.
>
>Greg
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