[linux-lvm] Max logical volume size 1TB or 2TB?

[Jay Weber]

Hmm, I could help out on this one also, since I've access to larger 72G
disks which require filling less space. :)

I'll give this a go soon hopefully and see if we can't sort this one out.
I'd definately be interested in getting all we can out of it. :)

On Thu, 10 May 2001, Andreas Dilger wrote:

> Date: Thu, 10 May 2001 00:33:37 -0600 (MDT)
> From: Andreas Dilger <adilger at turbolinux.com>
> Reply-To: linux-lvm at sistina.com
> To: linux-lvm at sistina.com
> Subject: Re: [linux-lvm] Max logical volume size 1TB or 2TB?
>
> Andrew Patterson writes:
> > I patched LVM 0.9.1_beta7 lvm.h source a little to get past the system
> > defined limits.
> >
> > These are the changes I made:
> >
> > #define LVM_LV_SIZE_MAX(a)      ( ( long long) LVM_PE_T_MAX * (a)->pe_size > (
> > long long) 1024*1024/SECTOR_SIZE*1024*1024*2 ? ( long long)
> > 1024*1024/SECTOR_SIZE*1024*1024*2 : ( long long) LVM_PE_T_MAX * (a)->pe_size)
> >
> > #define LVM_MAX_SIZE            ( 1024LU * 1024 / SECTOR_SIZE * 1024 * 1024*2)
>
> I presume the originals should not have the *2 on them?
>
> > goes to:
> >
> > #define LVM_LV_SIZE_MAX(a)      ( ( long long) LVM_PE_T_MAX * (a)->pe_size > (
> > long long) 1024*1024/SECTOR_SIZE*1024*1024*2 ? ( long long)
> > 1024*1024/SECTOR_SIZE*1024*1024*2 : ( long long) LVM_PE_T_MAX * (a)->pe_size)
> >
> > #define LVM_MAX_SIZE            ( 1024LU * 1024 / SECTOR_SIZE * 1024 * 1024*2)
>
> You probably want to go to something like (i.e. slightly less than 2GB):
>
> #define LVM_LV_SIZE_MAX(a)      ( ( long long) LVM_PE_T_MAX * (a)->pe_size > (
> long long) 1024*1024/SECTOR_SIZE*1024*2047 ? ( long long)
> 1024*1024/SECTOR_SIZE*1024*2047 : ( long long) LVM_PE_T_MAX * (a)->pe_size)
>
> #define LVM_MAX_SIZE            ( 1024LU * 1024 / SECTOR_SIZE * 1024 * 2047)
>
> The reason is that since we are talking about 512-byte sectors here, your
> original values are exactly 2^32, so this is probably overflowing a 32-bit
> value somewhere.  Since the Linux block layer limits you to 2TB anyways,
> it is not a real issue for the LVM limit to be slightly less than 2TB.
> How much less depends on how many more disks you have...  Probably any
> value <= 2^32-1 should be OK.
>
> Cheers, Andreas
> --
> Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
>                  \  would they cancel out, leaving him still hungry?"
> http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert
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