Date: Tue, 26 Jun 2001 10:40:49 -0700 From: "Kevin Oberman" <oberman@es.net> To: parv <parv_@yahoo.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: 2 freebsd slices on 1 disk. possible? Message-ID: <200106261740.f5QHenc17816@ptavv.es.net> In-Reply-To: Your message of "Sun, 24 Jun 2001 15:27:39 EDT." <20010624152739.A4442@moo.holy.cow>
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> Date: Sun, 24 Jun 2001 15:27:39 -0400
> From: parv <parv_@yahoo.com>
> Sender: owner-freebsd-questions@FreeBSD.ORG
>
>
>
> the only thing now holding be back is the difference between info
> provided by partition magic & fdisk. below is the output
> of fdisk w/ difference w/ p-magic (wrt cylinder position) listed...
[non-relevant data deleted]
> The data for partition 3 is:
> sysid 28,(unknown)
> start 9843120, size 7378560 (3602 Meg), flag 0
> beg: cyl 651/ sector 1/ head 0;
> end: cyl 1023/ sector 63/ head 239
>
> # partition magic diff:
> end: cyl 1138/ sector 63/ head 239
>
> The data for partition 4 is:
> sysid 15,(Extended DOS, LBA)
> start 17221680, size 2419200 (1181 Meg), flag 0
> beg: cyl 1023/ sector 1/ head 0;
> end: cyl 1023/ sector 63/ head 239
>
> # partition magic diff:
> beg: cyl 1139/ sector 1/ head 0;
> end: cyl 1298/ sector 63/ head 239
> --------------------------------------------------
>
> now question is: does the difference in cylinder numbers reported by
> fdisk & partition magic make any, well, difference?
>
> i have alredy read the man pages for fdisk & disklabel, just need
> reassurance.
This is a FreeBSD fdisk behavior when dealing with large disks which
are configured as LBA. Because the CHS values allowed for disks has a
limit of 1024 cyl, fdisk will only report values to 1023. Use of LBA
eliminates this.
You can safely ignore this. Just configure the slices for the desired
number of blocks and it should be fine.
Here is an fdisk for a 13 GB drive on another system, It's a full 13
GB slice, but the cylinder is shown as 1023.
The data for partition 1 is:
sysid 165,(FreeBSD/NetBSD/386BSD)
start 63, size 26687745 (13031 Meg), flag 80 (active)
beg: cyl 0/ sector 1/ head 1;
end: cyl 1023/ sector 63/ head 15
Note that 1024*63*15*512 is nowhere near 13 GB!
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman@es.net Phone: +1 510 486-8634
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