Achieve I/O alignment using LUN OS types

Contributors

To achieve I/O alignment with your OS partitioning scheme, you should use the recommended ONTAP LUN ostype value that most closely matches your operating system.

The partition scheme employed by the host operating system is a major contributing factor to I/O misalignments. Some ONTAP LUN ostype values use a special offset known as a “prefix” to enable the default partitioning scheme used by the host operating system to be aligned.

Note

In some circumstances, a custom partitioning table might be required to achieve I/O alignment. However, for ostype values with a “prefix” value greater than 0, a custom partition might create misaligned I/O.

The LUN ostype values in the following table should be used based on your operating system.

LUN ostype Prefix (bytes) Prefix (sectors) Operating system

windows

32,256

63

Windows 2000, 2003 (MBR format)

windows_gpt

17,408

34

Windows 2003 (GPT format)

windows_2008

0

0

Windows 2008 and later

linux

0

0

All Linux distributions

xen

0

0

Citrix XenServer

vmware

0

0

VMware ESX

solaris

1MB

2,048

Solaris

solaris_efi

17,408

34

Solaris

hpux

0

0

HP-UX

aix

0

0

AIX