[dm-devel] Device Mapper and unknown device.

[Saito Jun]

Hello everybody professional.
I am embarrassed.
What is this /dev/dm-1?
The cylinder is different though it is the same capacity.
And I newly made LUN.

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[root at ns01 ~]# fdisk -l
This doesn't look like a partition table
Probably you selected the wrong device.
dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 * 1 1305 10482381 7 HPFS/NTFS

Disk /dev/sdc: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdc1 * 1 1305 10482381 7 HPFS/NTFS

Disk /dev/dm-0: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/dm-0p1 * 1 1305 10482381 7 HPFS/NTFS

Disk /dev/dm-1: 10.7 GB, 10733958144 bytes
255 heads, 63 sectors/track, 1304 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

This doesn't look like a partition table
Probably you selected the wrong device.

Device Boot Start End Blocks Id System
/dev/dm-1p1 ? 10499 10499 0 65 Novell Netware 386
Partition 1 does not end on cylinder boundary.
/dev/dm-1p2 ? 13578 119522 850995205 72 unknown
Partition 2 does not end on cylinder boundary.
/dev/dm-1p3 ? 45382 79243 271987362 74 unknown
Partition 3 does not end on cylinder boundary.
/dev/dm-1p4 167628 167631 25817+ 0 empty
Partition 4 does not end on cylinder boundary.
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It explains the procedure.
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My Environment
/dev/sda [LocalDisk]
/dev/sdb [SAN External Disk]
/dev/sdc [SAN External Disk]

Configure Multipath
Edit /etc/multipath.conf
/etc/init.d/multipathd

Create Partition
fdisk /dev/sdb

Create Multipath block device
kpartx -a /dev/mapper/mpath0

Create File System
mke2fs -j /dev/mapper/mpath0p1

Mount
mount -t ext3 /dev/mapper/mpath0p1

Question
ls /dev/dm-1
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Regards,