10-01-2015
Other then stuff mentioned here i would like to make a general recommendation regarding disk devices in Linux.
If you present a disk for instance /dev/xxx, create a primary partition /dev/sda1 which you will use in your volume groups / filesystems / ASM and label it like that (LVM label or other) during fdisk operation.
Why partition ?
Initial sectors are for OS information.
Easier to see and correct possible errors which are out of LVM/ASM/filesystem scope.
Disks partitioned are quite obviously used for some service (LVM, ASM etc.), while non-partitioned are not, reducing possible risk of error during administrative work.
Using full devices will work as well on Linux systems, but due to reasons above i would suggest making one primary partition if you intend to use entire disk space.
As for multipath, use /dev/mapper when creating volume groups and such.
Also using sane names for storage luns in /etc/multipath.conf helps e.g /dev/mapper/databaselun looks much more human then /dev/mapper/mpathXY
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KPARTX(8) Linux Administrator's Manual KPARTX(8)
NAME
kpartx - Create device maps from partition tables
SYNOPSIS
kpartx [-a | -d | -l] [-v] wholedisk
DESCRIPTION
This tool, derived from util-linux' partx, reads partition tables on specified device and create device maps over partitions segments
detected. It is called from hotplug upon device maps creation and deletion.
OPTIONS
-a Add partition mappings
-r Readonly partition mappings
-r Read-only partition mappings
-d Delete partition mappings
-u Update partition mappings
-l List partition mappings that would be added -a
-p set device name-partition number delimiter
-f force creation of mappings; overrides 'no_partitions' feature
-g force GUID partition table (GPT)
-v Operate verbosely
-s Sync mode. Don't return until the partitions are created
EXAMPLE
To mount all the partitions in a raw disk image:
kpartx -av disk.img
This will output lines such as:
loop3p1 : 0 20964762 /dev/loop3 63
The loop3p1 is the name of a device file under /dev/mapper which you can use to access the partition, for example to fsck it:
fsck /dev/mapper/loop3p1
When you're done, you need to remove the devices:
kpartx -d disk.img
SEE ALSO
multipath(8) multipathd(8) hotplug(8)
AUTHORS
This man page was assembled By Patrick Caulfield for the Debian project. From documentation provided by the multipath author Christophe
Varoqui, <christophe.varoqui@opensvc.com> and others.
July 2006 KPARTX(8)