The maximum size limit [translation] LVM logical volumes
https://www.cnblogs.com/kerrycode/p/8662780.html
Foreword: This article is this blog Maximum Size Of A Logical Volume In LVM translation, please respect the original and the translation of the fruits of labor, those gentlemen freely reproduced, whatever the outcome, consciously indicate the source . Thank you !
English Original Address: https://www.walkernews.net/2007/07/02/maximum-size-of-a-logical-volume-in-lvm/
Translation Original Address: http://www.cnblogs.com/kerrycode/p/8662780.html
The maximum size of the Logical Volume Manager (Linux Logical Volume Manager) or LVM in a single logical volume (LV) is how much? (PE) to the physical size of the expansion unit how to dynamically adjust and modify existing volume group (VG) it?
Most likely, you see this article because you search these problems similar LVM FAS in Google. I hope this is what you want answers.
When creating VG of, a physical extension unit LVM volume group (VG) of the (Physical Extends abbreviation PE) size is fixed, the Linux command line option -s vgcreate command represented explicitly set the volume group (VG) physical volume ( PV) PE in size.
If you do not explicitly set the size of the PE, then, by default PE size of 4MB, but once this value is set, and if not, then rebuild VG, PE size can not be modified. This will involve data backup and recovery data on the logical volume.
On the current LVM2 - LVM version 2.02.06 (2006-05-12), Library version 1.02.07 (2006-05-11), driver version 4.5.0 - no LVM commands or tool, even in HPUX used vgmodify, or can not dynamically adjust or change the size of an existing LVM PE VG's online mode!
Therefore, we recommend proper plan before creating LVM volume group, for example, if the data stored in the logical volume is likely in the near future than 300G size, then when you create VG, you can not set the PE size of 4MB
Linux visual conceptual diagram of the Logical Volume Manager or LVM.
The maximum size of the Linux LVM logical volume is how much?
Why is the maximum size of a logical volume is limited?
In order to limit the Linux kernel memory usage of each logical volume (LV) 65,536 limited physical extents (PE) to. Therefore, LVM in PE will directly determine the size of the maximum size of the logical volume (LV) of! For example, 4MB PE size (default size PE) single logical volume (LV) is limited to 256GB, 16MB PE size will limit the single LV growth than 1TB, and the like.
In addition to the PE size factor, the maximum size of a single LV is also affected by CPU architecture and the Linux kernel version limitations:
Linux kernel version 2.4.x maximum LV size is limited to 2TB.
In some previous older 2.4.x Linux kernel, the maximum LV size is limited to 1TB (Signed by the integer block layer causes problems caused by the integer signedness problems in the block layer).
Combination of 32-bit CPU and the 2.6.x Linux kernel version, the logical volume size is limited maximized when 16TB.
For Linux 2.6.x kernel running on 64-bit CPU, maximum LV size is 8EB (At this terrible mass storage!)
Translated, here is my Google search to describe the information on kernel version and CPU architectures to limit the size of the logical volume. for reference only.
· For 2.4 based kernels, the maximum LV size is 2TB. For some older kernels, however, the limit was 1TB due to signedness problems in the block layer. Red Hat Enterprise Linux 3 Update 5 has fixes to allow the full 2TB LVs. Consult your distribution for more information in this regard.
·
· For 32-bit CPUs on 2.6 kernels, the maximum LV size is 16TB.
·
· For 64-bit CPUs on 2.6 kernels, the maximum LV size is 8EB. (Yes, that is a very large number.)
-------------------------------------------------- Dividing line------------------------------------------------ -------------
Once we created a LV over 265G, but PE Size to 4M, this makes me very confused, looked at the statistics behind the discovery, used to have each logical volume (LV) has a limit of 65,536 physical extents (PE), but LVM 2 from the beginning, there is no limit of the number of PE , this only as a supplement to the above translation of the article. In particular the following reads as follows:
Those limits (65536 LE per LV) does not apply to LVM 2 and 2.6 kernel. Your LV can have much more LE (I dont know if there is even reachable limit for this). One and only feedback (if you can notice this) is that userspace programs for managing LVM works _little_ slower, when there is enormous number od LE to administrate. I tested it with 4GB LV on 16MB LE (but I didnt see difference)
Original Address: https://www.redhat.com/archives/linux-lvm/2005-January/msg00059.html