From mboxrd@z Thu Jan  1 00:00:00 1970
Message-Id: <200610032013.k93KD9m20820@zamenhof.cs.utwente.nl>
To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu>
Subject: Re: [9fans] kenfs config? (was: OT: scsi sense error code hardware
	error 40 83?)
In-reply-to: Your message of "Tue, 03 Oct 2006 14:17:04 -0400."
	<8fd802a4a0bcc60a27f43346bbccf0c5@plan9.bell-labs.com> 
References: <8fd802a4a0bcc60a27f43346bbccf0c5@plan9.bell-labs.com> 
From: Axel Belinfante <Axel.Belinfante@cs.utwente.nl>
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Content-ID: <20814.1159906388.1@zamenhof.cs.utwente.nl.cs.utwente.nl>
Date: Tue,  3 Oct 2006 22:13:09 +0200
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> I can't help with the sense code; I suspect that the component number
> (NN) is specific to the manufacturer and device.

I suspected that too. unfortunately, even though the manufactor site
still lists the disk and has info like jumper settings, it doesn't
have those details. maybe their 'scsimax' thing will tell me something.

> As for replacing your cache disk, yes, your plan sounds right.  Since
> your entire cache is being replaced, there is no memory anywhere else
> of how big it was, so you can replace it with a disk or disks of any
> size.  "recover main" rebuilds your cache disk from the (fake) worm.

thanks for confirming.


different question:
what is the safe procedure to add one (or more?) mirror disks to the
fake cached worm of an existing kenfs? like one mirror disk for the
fake worm, and a different one to the cache?

I gues your answer above implies that for the cache it would be ok to
just configure the new filesys with mirror-ed cache and then recover.

The fsconconfig man page seems to suggest that for the mirror
of the fake worm it would also be sufficient to just specify
the mirror, with the existing fake worm device at the left.

	{device...}
		A pseudo-device formed from the mirroring of the first
		device in the list onto all the others. [...]

Is this right? or is an explicit copydev of the fake worm needed
(or advisable?)


one more:
when extending an existing config say on w0, one does
  config w0    (identify config location + erase current)
  mention all old config items
  add new config items
  end
right? or is there a way to just extend an existing config?


one last question, mere curiosity:
fsconfig(8) also says:
    Copydev will copy the device from-dev to the device to-dev.
    block by block, and panic.

why the panic? to be allowed (forced?) to reboot and config?


sorry for all these questions, but configuring a kenfs is not
something I (any of us?) daily do, and experience some years
ago taught me to be a bit careful (yeah, it's in the archives) 
(not that I learned enough to set up mirroring before I need it :-(

Thanks, a lot!
Axel.