Date: Mon, 18 Sep 2000 23:59:14 -0400 (EDT) From: Marc Tardif <intmktg@CAM.ORG> To: "Aleksandr A.Babaylov" <babolo@links.ru> Cc: "Daniel C. Sobral" <dcs@newsguy.com>, freebsd-hackers@FreeBSD.ORG, freebsd-fs@FreeBSD.ORG Subject: Re: device naming convention Message-ID: <Pine.LNX.4.10.10009182355360.6707-100000@Gloria.CAM.ORG> In-Reply-To: <200009190132.FAA01937@aaz.links.ru>
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> 0cicuta/home/babolo(9)#dd of=/dev/wd0s2 if=/dev/zero bs=660b > 1cicuta/home/babolo(11)#od -b /dev/wd0s2 [ snip ] > Why I use 2.2.7 for test? > Because of my lovely 4.1-STABLE is extremly unstable with content of > ad0s2 (wd0s2) above and silently reboot after the first dd in the test above. > Assuming my wd0s2 is still unused and of size 0, 3.5-STABLE also crashes in the test above (no disk activity, ctrl-c doesn't work, alt-f# doesn't work either). Perhaps it eventually reboots, but I wasn't patient enough to wait that long. One solution to this problem is to specify the count blocks after which dd returns properly but still no bytes are copied. > What is slices content? > s1 - almost right FreeBSD label > s2 - not a right FreeBSD label but similar enough to label. > s3 - no label or similar at all. > How to do such a content that screw the system? > This is my way for this test: > - shorten s2 to 3 cilinder. > - disklabel -w -r wd0s2 fd360 > - restore s2 size. > I don't understand this last part, probably because I don't have much experience with labelling and partitioning. Please excuse my questions if they seem basic, but I am fairly new to disks: - how can s2 be "similar enough to label" if it is recognised as "sysid 0,(unused)" by fdisk? - how did you create s2 exactly, in order to make it "similar enough to label" yet remain unused? - how did you create s3 and s4 exactly? - why is s3 not similar at all if it is recognised as a FreeBSD slice by fdisk? - what do you mean by shortening s2 to 3 cylinders? Do you mean s2 should start at the third cylinder? - is there any reason you chose to label wd0s2 as fd360? - how should s2 size be restored? maybe: dd of=/dev/wd0s2 if=/dev/null bs=660b? > How can you guarantee that occasionally some > bits in slice do not fraud FreeBSD > if used for arbitrary bits? > Do not use slice begin at all. > I also didn't quite understand what is wrong with using the slice begin. Your octal dump showed how the first 017343 bytes were not nulls, but why? Is there a fixed number of bytes that should be skipped, or should this number be system dependent and tested manually? To avoid using the slice begin, could the first label be defined at a proper offset to skip the slice begin? Marc To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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