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FreeBSD: Mounting extended/logical fat32 partition

Last response: in Linux/Free BSD
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June 3, 2011 4:27:42 AM

I'm having some real trouble getting a fat32 logical partition within an extended partition. First of all, here's the fdisk output:

Quote:
# fdisk ad5s4s2
******* Working on device /dev/ad5s4s2 *******
parameters extracted from in-core disklabel are:
cylinders=9132 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=9132 heads=16 sectors/track=63 (1008 blks/cyl)

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 7 (0x07),(NTFS, OS/2 HPFS, QNX-2 (16 bit) or Advanced UNIX)
start 63, size 9205182 (4494 Meg), flag 0
beg: cyl 1023/ head 254/ sector 63;
end: cyl 1023/ head 254/ sector 63
The data for partition 2 is:
sysid 5 (0x05),(Extended DOS)
start 29672055, size 61432560 (29996 Meg), flag 0
beg: cyl 1023/ head 254/ sector 63;
end: cyl 1023/ head 254/ sector 63
The data for partition 3 is:
sysid 0 (0000),(unused)
start 24897, size 0 (0 Meg), flag 0
beg: cyl 0/ head 0/ sector 0;
end: cyl 370/ head 0/ sector 50
The data for partition 4 is:
<UNUSED>


I'm trying to get at partition 2 -- that 29996Meg partition. But when I try to mount:

Quote:
# mount -t msdosfs /dev/ad5s4s2 /mnt/music
mount_msdosfs: /dev/ad5s4s2: Invalid argument


What am I missing?

I do have geom_mbr.ko loaded.
June 3, 2011 7:58:36 AM

I believe that you are using the incorrect device name. Try:

/dev/ad5s5

(assuming that your FAT partition is the first or only logical drive in your extended partition. If not it will be /dev/ad5s6, etc.) There is a slight complication here in that what Windows calls a "partition" is what BSD calls a "slice".

This link explains it more clearly.
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June 10, 2011 12:53:43 AM

No good answers here; admin should feel free to close.
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June 10, 2011 10:04:19 AM

I'm curious to know why the mount failed when you used the correct device name. I wonder if you could post the error message that you get when you try to mount /dev/ad5s5.
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June 10, 2011 2:54:03 PM

There was no /dev entry for ad5s5.
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June 10, 2011 3:39:19 PM

Strange. Read the FreeBSD documentation and you'll see that extended partitions are numbered s5, s6, etc. Mind, the fdisk that you reported is odd as the disk is just /dev/ad5.

The first physical partition (slice in BSD speak) is /dev/ad5s1; the partitions within this are /dev/ad5s1a, etc. And the first extended partition is (or should be) /dev/ad5s5.
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June 10, 2011 4:15:37 PM

Yeah, thanks -- I've read the FreeBSD documentation; in fact, I read it before asking this question. I don't know why it wasn't in /dev, but it wasn't. I tried mounting every single ad5 entry in /dev; none worked.

The ultimate resolution was to go back into Windows and make that a primary partition versus a logical partition. That did the job -- shame FreeBSD couldn't, though. It's behavior is entirely unexplained at this point.
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