[dm-devel] Device Mapper and unknown device.

[malahal at us.ibm.com]

Find the major/minor number of /dev/dm-1 (most likely 253,1). Then run
"dmsetup table --major <major> --minor <minor>".

It is most likely same as your mpath0p1

Or see the major/minor of mpath0p1.

Thanks, Malahal.

Saito Jun [cartman at mbs.sphere.ne.jp] wrote:
> 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.
> 
> -------------------------
> [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.
> ---------------------------------
> 
> 
> It explains the procedure.
> --------------------
> 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
> ---------------------
> 
> Regards,
> 
> --
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