Date: Thu, 18 Feb 2010 06:52:21 +0800 From: Aiza <aiza21@comclark.com> To: Bob Willcox <bob@immure.com> Cc: questions list <freebsd-questions@freebsd.org> Subject: Re: fdisk fails with "Class not found" Message-ID: <4B7C7325.3020002@comclark.com> In-Reply-To: <20100217185846.GA85769@rancor.immure.com> References: <20100217185846.GA85769@rancor.immure.com>
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Bob Willcox wrote: > I am trying to change the sysid of a slice (partition) on my disk from 5 to > 165. When it gets to the point of writing sector 0 it always fails with: > > fdisk: Class not found > fdisk: Failed to write sector zero > > Can someone please tell me what this means, and how do I fix it? > I have included the output from an fdisk attempt below. > > Thanks, > Bob > > root@tavion:10 /usr/home/bob> fdisk -uv > ******* Working on device /dev/ad4 ******* > parameters extracted from in-core disklabel are: > cylinders=969021 heads=16 sectors/track=63 (1008 blks/cyl) > > Figures below won't work with BIOS for partitions not in cyl 1 > parameters to be used for BIOS calculations are: > cylinders=969021 heads=16 sectors/track=63 (1008 blks/cyl) > > Do you want to change our idea of what BIOS thinks ? [n] > Media sector size is 512 > Warning: BIOS sector numbering starts with sector 1 > Information from DOS bootblock is: > The data for partition 1 is: > sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD) > start 63, size 524286945 (255999 Meg), flag 80 (active) > beg: cyl 0/ head 1/ sector 1; > end: cyl 1023/ head 15/ sector 63 > Do you want to change it? [n] > The data for partition 2 is: > sysid 5 (0x05),(Extended DOS) > start 524297340, size 452470725 (220932 Meg), flag 0 > beg: cyl 1023/ head 255/ sector 63; > end: cyl 1023/ head 14/ sector 63 > Do you want to change it? [n] y > Supply a decimal value for "sysid (165=FreeBSD)" [5] 165 > Supply a decimal value for "start" [524297340] > Supply a decimal value for "size" [452470725] > Explicitly specify beg/end address ? [n] > sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD) > start 524297340, size 452470725 (220932 Meg), flag 0 > beg: cyl 968/ head 4/ sector 1; > end: cyl 311/ head 14/ sector 63 > Are we happy with this entry? [n] y > The data for partition 3 is: > <UNUSED> > Do you want to change it? [n] > The data for partition 4 is: > <UNUSED> > Do you want to change it? [n] > Partition 1 is marked active > Do you want to change the active partition? [n] > > We haven't changed the partition table yet. This is your last chance. > parameters extracted from in-core disklabel are: > cylinders=969021 heads=16 sectors/track=63 (1008 blks/cyl) > > Figures below won't work with BIOS for partitions not in cyl 1 > parameters to be used for BIOS calculations are: > cylinders=969021 heads=16 sectors/track=63 (1008 blks/cyl) > > Information from DOS bootblock is: > 1: sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD) > start 63, size 524286945 (255999 Meg), flag 80 (active) > beg: cyl 0/ head 1/ sector 1; > end: cyl 1023/ head 15/ sector 63 > 2: sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD) > start 524297340, size 452470725 (220932 Meg), flag 0 > beg: cyl 968/ head 4/ sector 1; > end: cyl 311/ head 14/ sector 63 > 3: <UNUSED> > 4: <UNUSED> > Should we write new partition table? [n] y > fdisk: Class not found > fdisk: Failed to write sector zero > The 'Class not found' you can ignore. Fdisk still worked. Try dd if=/dev/zero of=/dev/xxx count=2 to remove the MBR them do fdisk -I /dev/xxx command
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