[linux-lvm] snapshot with bigmem broken
arechenberg at shermfin.com
Wed May 21 10:45:02 UTC 2003
I have HIGHMEM enabled on my kernel but I have to limit the memory to
~6GB for snapshots to work. I added mem=6000M to my kernel command line
and snapshots work fine.
I also found this thread on the LKML that has a patch that may fix the
The only machine we have that has >4GB RAM is a production box and I
really don't want to test something in production (call me crazy :) ).
Here are my specs:
Hope this helps,
On Fri, 2003-05-16 at 08:38, Lauro, John wrote:
> > > I did more testing, and it appears that snapshots in LVM will not
> > > with either 4GB or or 64GB support enabled in the kernel under
> > > This includes both LVM 1.0.7 or the latest LVM2.
> > >
> > That's a known issue. You are faced with a VM flaw.
> > I presume that it's not LVM snapshots only bacause HIGHMEM is
> > basically broken.
> Can you give more specifics/examples/web links/etc? Does this mean I
> should avoid LVM completely with HIGHMEM? What if any other problems
> should I expect with LVM (and/or other software)?
> > > Is there anyone using LVM snapshots with 64GB RAM support (or even
> > > RAM support, as snapshots would be good for at least our medium
> > > servers if not our large ones)? Is so, let me know the kernel
> > > and LVM version you are using so that I can try it.
> > Probably not, because the system lifelocks on bounce buffers (which
> > the sympton of the principle HIGHMEM bug).
> > Obviously not a lot of HIGHMEM users out there raising priorities to
> > this.
> Is this easy to reproduce? If so, how? Sounds like I am either a
> lucky early adopter of a >4GB Libux system, and/or the problem is rare
> even on HIGHMEM systems?
> linux-lvm mailing list
> linux-lvm at sistina.com
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Andrew Rechenberg <arechenberg at shermfin.com>
Infrastrucutre Team, Sherman Financial Group
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