Fdisk the device, drop and recreate the partition with desired size. I’ll also do the 64k block alignment do get the maximum performance.
Before deleting partition check start sector for partition. Because partition may start from 63 sector (not aligned) or 64 sector (aligned).
# fdisk /dev/mapper/mpath21
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): p
Disk /dev/mapper/mpath21: 7516 MB, 7516192768 bytes
255 heads, 63 sectors/track, 913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xab317070
Device Boot Start End Blocks Id System
/dev/mapper/mpath21p1 1 783 6289415+ 83 Linux
Partition 1 has different physical/logical beginnings (non-Linux?):
phys=(0, 1, 1) logical=(0, 1, 2)
--------------Here we check start sector for partition
Command (m for help): x
Expert command (m for help): p
Disk /dev/mapper/mpath21: 255 heads, 63 sectors, 913 cylinders
Nr AF Hd Sec Cyl Hd Sec Cyl Start Size ID
1 00 1 1 0 254 63 782 64 12578831 83
Partition 1 has different physical/logical beginnings (non-Linux?):
phys=(0, 1, 1) logical=(0, 1, 2)
2 00 0 0 0 0 0 0 0 0 00
3 00 0 0 0 0 0 0 0 0 00
4 00 0 0 0 0 0 0 0 0 00
Expert command (m for help): r
Command (m for help): d
Selected partition 1
Command (m for help): p
Disk /dev/mapper/mpath21: 7516 MB, 7516192768 bytes
255 heads, 63 sectors/track, 913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xab317070
Device Boot Start End Blocks Id System
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-913, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-913, default 913):
Using default value 913
Command (m for help): x
Expert command (m for help): b
Partition number (1-4): 1
New beginning of data (1-14667344, default 63): 64
Expert command (m for help): p
Disk /dev/mapper/mpath21: 255 heads, 63 sectors, 913 cylinders
Nr AF Hd Sec Cyl Hd Sec Cyl Start Size ID
1 00 1 1 0 254 63 912 64 14667281 83
Partition 1 has different physical/logical beginnings (non-Linux?):
phys=(0, 1, 1) logical=(0, 1, 2)
2 00 0 0 0 0 0 0 0 0 00
3 00 0 0 0 0 0 0 0 0 00
4 00 0 0 0 0 0 0 0 0 00
Expert command (m for help): r
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
False duplicate IP address detected on Microsoft Windows Vista and later virtual machines on ESX/ESXi when using Cisco devices on the environment (1028373)
Starting the server from the user ID that owns the server instance