[linux-lvm] Max LV size

[linux-lvm] Max LV size

[Alexander Lazarevich]

I've got a RAID 5 array which is 500GB. It's on a red hat 7.3 system
(2.4.18-3 kernel) using sistina LVM 1.0.3. I've already got my VG set up,
and I'm now crreating the LV's, but I've got a problem.

vgdisplay -v tells me the max LV size is 255GB. So I figured I'd decrease
the number of Max LV's (currently at 256) to 128, and then that would
increase the size that each LV could be. But when I do a "vgchange -l 128
blah", it just stops and says "segmentation fault".

What gives? I really hope 255GB isn't a limit. Any ideas?

Thanks in advance,

Alex
---                                                        ---
   Alex Lazarevich | Systems | Imaging Technology Group
   alazarev@itg.uiuc.edu | (217)244-1565 | www.itg.uiuc.edu
---                                                        ---

Re: [linux-lvm] Max LV size

[Jose Luis Domingo Lopez]

On Monday, 11 November 2002, at 16:10:05 -0600,
Alexander Lazarevich wrote:

> vgdisplay -v tells me the max LV size is 255GB. So I figured I'd decrease
> the number of Max LV's (currently at 256) to 128, and then that would
> increase the size that each LV could be. But when I do a "vgchange -l 128
> blah", it just stops and says "segmentation fault".
> 
> What gives? I really hope 255GB isn't a limit. Any ideas?
> 
Yes, just read the documentation :-). From man vgcreate:

       -s, --physicalextentsize PhysicalExtentSize[kKmMgGtT]
              Sets  the  physical extent size on physical volumes
              of this volume group.  A size suffix (k  for  kilo
              bytes up to t for terabytes) is optional, megabytes
              is the default if no suffix is present.  Values can
              be  from  8 KB to 16 GB in powers of 2. The default
              of 4 MB causes maximum LV sizes of  ~256GB  because
              as  many  as  ~64k extents are supported per LV. In
              case larger maximum LV sizes  are  needed  (later),
              you  need  to  set the PE size to a larger value as
              well. Later changes of the PE size in  an  existing
              VG are not supported.

Hope it helps.

-- 
Jose Luis Domingo Lopez
Linux Registered User #189436     Debian Linux Woody (Linux 2.4.19-pre6aa1)

[linux-lvm] max LV size

[Alexander Lazarevich]

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@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
---                                                               ---

Re: [linux-lvm] max LV size

[Heinz Mauelshagen]

On Wed, Mar 31, 2004 at 01:33:23PM -0600, Alexander Lazarevich wrote:
> 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@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?

It can. That limitation is gone in Linux 2.6.

> 
> Thanks in advance,
> 
> Alex
> ---                                                               ---
>    Alex Lazarevich | Systems Administrator | Imaging Technology Group
>     Beckman Institute | University of Illinois | www.itg.uiuc.edu
> ---                                                               ---
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

-- 

Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

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Heinz Mauelshagen                                 Red Hat GmbH
Consulting Development Engineer                   Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@RedHat.com                            +49 2626 141200
                                                       FAX 924446
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