Re: FAQ: 14.21.5 - Softraid notes

2016-02-22 Thread Nick Holland 
On 02/22/16 10:46, Theo Buehler wrote:
>>   Note that we did not specify the altroot device by DUID, but by device
>>   name. We probably want to be pushing from the boot device to the
>>   secondary device, which can end up changing if the drive order is
>>   changed. For this reason, you may want to specify the root and altroot
>>   in /etc/fstab as a device name, not a DUID. 
> 
> To be clear: the reason I'm hesitating is that I have no idea whether
> this really is sound advice or not.

Today, probably better to do bootable softraid (which was still fairly
primitive when I wrote that).

However, given the root partition, altroot partition and the rest as
softraid, yes, think about it a bit -- you want your / device to be
whatever is available as your '0' device, not a DUID that failed.

So let's say we got this:
65453c66b41bb710.a / ffs rw,softdep 1 1
034f77b0c2a1fe2e.d /altroot ffs xx 0 0

Now, 65453c66b41bb710 fails.
Your new root is 034f77b0c2a1fe2e.a, except it isn't, because you
hard-coded the old root into both copies of fstab.  Works much better if
that were saying "/dev/sd0a" instead (though there are still failure
cases -- if the old boot drive can't boot, but still shows up as sd0,

But bootable SR is still probably the way to go.

Oververbose, over documentation.  Nuke it.

Nick.

Re: FAQ: 14.21.5 - Softraid notes

2016-02-22 Thread Theo Buehler 
>   Note that we did not specify the altroot device by DUID, but by device
>   name. We probably want to be pushing from the boot device to the
>   secondary device, which can end up changing if the drive order is
>   changed. For this reason, you may want to specify the root and altroot
>   in /etc/fstab as a device name, not a DUID. 

To be clear: the reason I'm hesitating is that I have no idea whether
this really is sound advice or not.

Re: FAQ: 14.21.5 - Softraid notes

2016-02-22 Thread Theo Buehler 
> Out of curiosity: What is the rationale behind the last sentence in
> FAQ: 14.21.5 - Softraid notes:
> "You may not want to specify the root device by DUID."
> 
> I dare to ask as the installer sets DUIDs for every partition incl.
> "/". With this in mind I wonder why the root device should not be
> specified by the DUID. This sentence lacks at least a hint on why not.

Yeah, this is unfortunate, I'll have to think a bit how to improve this
situation..

> (Maybe it is just a misinterpretation of "may not" in this context -
> to me this reads as "should not" like "better don't do it".)

Does

"There are legitimate reasons not to specify the root device by DUID."

make more sense to you? I'd say it is roughly equivalent.

There is a brief explanation for this at the very end of section 14.20:

  Note that we did not specify the altroot device by DUID, but by device
  name. We probably want to be pushing from the boot device to the
  secondary device, which can end up changing if the drive order is
  changed. For this reason, you may want to specify the root and altroot
  in /etc/fstab as a device name, not a DUID.

FAQ: 14.21.5 - Softraid notes

2016-02-22 Thread Stefan Wollny 
Hi there!

Out of curiosity: What is the rationale behind the last sentence in FAQ: 
14.21.5 - Softraid notes:
"You may not want to specify the root device by DUID."

I dare to ask as the installer sets DUIDs for every partition incl. "/". With 
this in mind I wonder why the root device should not be specified by the DUID. 
This sentence lacks at least a hint on why not.

(Maybe it is just a misinterpretation of "may not" in this context - to me this 
reads as "should not" like "better don't do it".)

TIA.

Best,
STEFAN