[sclug] LVM & 2Tb limit

[Alex Butcher]

On Tue, 15 Feb 2005, Alan Pearson wrote:

> I've read that kernel 2.4 suffers from a 2 TB limitation on Block devices.
> I need to create a logical volume of around 12TB on a RHEL 3.0 system, which 
> also runs kernel 2.4 (albeit a RH kernel).

First of all, install the kernel src.rpm and check whether RH have
integrated the various large fs/block device patches. I'm pretty sure that's
the sort of thing they've done in the RH_E_L kernel, and I'm pretty sure
I've seen the patches in the RH7.2 kernel and the like.

<http://www.redhat.com/software/rhel/3features/kernel/> seems to suggest
that this is the case (see third bullet point from the end of the list), but
it does seem to be a bit contradictory.

<https://www.redhat.com/archives/nahant-beta-list/2004-October/msg00004.html>
also looks like a good place to start reading (found using 'RHEL3 TB "file
system" site:redhat.com' as the search term).

> Has anyone any ideas if this is possible ? Is this limitation eliminated
> in kernel 2.6 / LVM 2?

See above.

> Also is there any disadvantage to having such a large filesystem (I'm going 
> with reiserfs (I don't want to hear about ext3 !))

Off the top of my head:

- fsck times
- all your eggs in one basket

> The files that are stored there will be GBs in size so I'm not imaging 
> hundreds of thousands of files.

Consider tweaking the 'blocks-per-inode' setting when creating the
filesystem.

> Thanks
> AlanP

HTH,
Alex.
-- 
Alex Butcher      Brainbench MVP for Internet Security: www.brainbench.com
Bristol, UK                      Need reliable and secure network systems?
PGP/GnuPG ID:0x271fd950                         <http://www.assursys.com/>