[Translation] maximum logical volume size limit in LVM, lvm Logic

[Translation] maximum logical volume size limit in LVM, lvm Logic

 

This article is A translation Of Maximum Size Of A Logical Volume In LVM on this blog. Please respect the original and labor achievements Of the translation, and those who reprint them at will clearly indicate the source. Thank you!

 

Https://www.walkernews.net/2007/07/02/maximum-size-of-a-logical-volume-in-lvm/

 

Http://www.cnblogs.com/kerrycode/p/8662780.html

 

What is the maximum size of a Logical Volume (LV) in a Linux Logical Volume Manager or LVM? How can I dynamically adjust and modify the physical expansion unit (PE) of an existing volume group (VG?

 

It is very likely that you saw this article because you searched for these similar lvm fas issues on Google. I hope these are the answers you want.

 

When creating VG, the Physical Extension Unit (PE) of the LVM volume group (VG) is fixed. In the Linux Command Line, option-s of the vgcreate command explicitly sets the PE size on the physical volume (PV) on the volume group (VG.

 

If you do not explicitly set the PE size, the default PE size is 4 MB. However, once this value is set, the PE size cannot be modified without recreating the VG. This will involve data backup and data recovery on logical volumes.

 

For LVM2, the LVM version is 2.02.06 (), the Library version is 1.02.07 (), the driver version is 4.5.0-there is no LVM command or tool, and even vgmodify is used in HPUX, the lvm pe size of the existing VG cannot be adjusted or changed dynamically or in online mode!

 

Therefore, it is recommended that you plan properly before creating an LVM volume group. For example, if the data stored in the logical volume is likely to exceed GB in the near future, when creating the VG, the PE size cannot be set to 4 MB.

 

A visual conceptual diagram of the Linux logical volume manager or LVM.

 

 

 

What is the maximum logical volume size in Linux LVM?

 

Why is the maximum logical volume size limited?

 

 

To limit the Linux kernel memory usage, each logical volume (LV) has a limit of 65,536 physical disk areas (PES. Therefore, the PE size in LVM directly determines the maximum size of the logical volume (LV! For example, the size of a 4 mb pe (default PE size) is limited to 256 GB for a single logical volume (LV), and the size of a 16 mb pe is limited to more than 1 TB for a single LV, and so on.

 

In addition to the PE size, the maximum size of a single LV is also limited by the CPU architecture and Linux kernel version:

 

Linux Kernel version 2.4.x limits the maximum LV size to 2 TB.

 

In earlier linux kernels earlier than 2.4.x, the maximum LV size is limited to 1 TB (caused by the integer signature problem in the block layer caused by the integer signedness problems in the block layer ).

 

The combination of 32-bit CPU and Linux kernel 2.6.x maximizes the logical volume size by 16 TB.

 

For Linux kernel 2.6.x running on 64-bit CPUs, the maximum LV size is 8 EB (this is a terrible Large Storage Capacity !)

 

 

 

After the translation is complete, the following is a description of the logical volume size limit on the kernel version and CPU architecture I found on Google. For reference only.

 

 

· For 2.4 based kernels, the maximum LV size is 2 TB. for some older kernels, however, the limit was 1 TB due to signedness problems in the block layer. red Hat Enterprise Linux 3 Update 5 has fixes to allow the full 2 TB LVs. consult your distribution for more information in this regard.

·

· For 32-bit CPUs on 2.6 kernels, the maximum LV size is 16 TB.

·

· For 64-bit CPUs on 2.6 kernels, the maximum LV size is 8EB. (Yes, that is a very large number .)