[linux-lvm] max LV size

Alexander Lazarevich alazarev at itg.uiuc.edu
Wed Mar 31 19:33:23 UTC 2004


Hi,

Using lvm-1.0.3-15 on RHEL3-AS, kernel 2.4.21-9.0.1.ELsmp.

I've got two SCSI devices attached to the system, each one is 1.74TB in 
size. I want to make a single ext3 filesystem out of those devices. So I'm 
using LVM to create a logical volume (3.48TB) out of those devices:

Even though I set the PE size to 512MB ("vgcreate -s512 /dev/sda 
/dev/sdb"), and I can see the VG size is correct (3.18TB), the maximum LV 
size is still 2TB:

#vgdisplay
[root at xxxxxx root]# vgdisplay
--- Volume group ---
VG Name               test-vg
VG Access             read/write
VG Status             available/resizable
VG #                  0
MAX LV                256
Cur LV                0
Open LV               0
MAX LV Size           2 TB
Max PV                256
Cur PV                2
Act PV                2
VG Size               3.18 TB
PE Size               512 MB
Total PE              6510
Alloc PE / Size       0 / 0
Free  PE / Size       6510 / 3.18 TB
VG UUID               dU1Xjg-w0Y4-aeh2-yU4l-Wo7g-Lewx-r6l1cT
 
Later in the man pages, it says something briefly about a 2TB block device 
limit in linux 2.4:

#man vgcreate
"There is also (as of Linux 2.4) a kernel limitation of 2TB per block 
device."

Is an LV a "block device" and is this why I can't seem to create an LV 
bigger than 2TB? If this is the problem, then LVM2 wouldn't even help, 
would it? Is it really true that no one can create a non-softwareRAID 
filesystem bigger than 2TB on linux 2.4? That just can't be true. Can it?

Thanks in advance,

Alex
---                                                               ---
   Alex Lazarevich | Systems Administrator | Imaging Technology Group
    Beckman Institute | University of Illinois | www.itg.uiuc.edu
---                                                               ---




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