Date: Wed, 25 Aug 1999 10:28:50 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: "Mark J. Taylor" <mtaylor@cybernet.com> Cc: current@FreeBSD.ORG Subject: Re: newfs of a ccd failing? Message-ID: <199908251728.KAA11414@apollo.backplane.com> References: <XFMail.990825130114.mtaylor@cybernet.com>
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:I've had this problem since at least FreeBSD 3.1-RELEASE (it works in
:2.2.7/2.2.8). Same problem in 3.2-RELEASE and -current (as of last night).
:
:Can someone reproduce this error? I can't believe that you can't newfs
:a ccd... did I miss something?
:[snip]
:newfs /dev/rccd0c
:Warning: 16 sector(s) in last cylinder unallocated
:/dev/rccd0c: 204784 sectors in 50 cylinders of 1 tracks, 4096 sectors
: 100.0MB in 4 cyl groups (16 c/g, 32.00MB/g, 6272 i/g)
:super-block backups (for fsck -b #) at:
: 32, 65568, 131104, 196640
:newfs: ioctl (WDINFO): No such process
:newfs: /dev/rccd0c: can't rewrite disk label
You have two problems.
First, you are using a VN device for which you have enabled
labels. The label is stored in the first few sectors of the
VN's device.
You have then created a CCD on top of the VN device and
tried to create a label in it as well, using 'c' which
starts at offset 0.
The two label areas overlap. Creating a real label under
the ccd device will destroy the VN device's label.
Problem #2: the ccd device creates a 'garbage' label. It
does not create a real label.
newfs tries to rewrite the real label, but since no label
exists it gets an error.
You can create a real label like this:
disklabel ccd0 > /tmp/ccd0.label
disklabel -R -r ccd0 /tmp/ccd0.label
And then your newfs will not generate any errors.
BUT, you've just destroyed the VN label by doing this.
Ok, so how to fix?
* Create a 'd' partition in the VN device which is offset
by 16 sectors. 'disklabel -e vn0'
8 partitions:
# size offset fstype [fsize bsize bps/cpg]
c: 204800 0 unused 0 0 # (Cyl. 0 - 99)
d: 204784 16 4.2BSD 0 0 0 # (Cyl. 0*- 99*)
* Configure the ccd on top of the vn device's 'd' partition.
* Create a real label for the ccd
* newfs your filesystem.
:
:I believe that there is a problem in/near ufs/ufs/ufs_disksubr.c where it
:says that it requires an existing disklabel before it writes a new one.
:If I change the "#if 1" to an "#if 0" in it, then I don't get this failure.
It's probably safer for the system to generate an error if no
preexisting label exists. It is fairly easy to create a label.
The CCD device is rather archaic and needs to be babied a bit when
you use it on top of artificially constructed devices. The real
problem is that the CCD device requires a block device with an
fstype of '4.2BSD'. If we got rid of that requirement then you
could run it on top of a 'raw' VN device (without -s labels). If
the ccd device didn't try to fake up its label then newfs would
not attempt to rewrite it and thus would not complain.
-Matt
Matthew Dillon
<dillon@backplane.com>
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