From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Heinz J . Mauelshagen" Subject: Re: [linux-lvm] snapshot with bigmem broken Message-ID: <20030520093419.C9086@sistina.com> References: <37885B2630DF0C4CA95EFB47B30985FB020EBDA8@exchange-1.umflint.edu> Mime-Version: 1.0 In-Reply-To: <37885B2630DF0C4CA95EFB47B30985FB020EBDA8@exchange-1.umflint.edu>; from jlauro@umflint.edu on Fri, May 16, 2003 at 08:38:23AM -0400 Sender: linux-lvm-admin@sistina.com Errors-To: linux-lvm-admin@sistina.com Reply-To: linux-lvm@sistina.com List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: Date: Tue May 20 02:43:02 2003 List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-lvm@sistina.com On Fri, May 16, 2003 at 08:38:23AM -0400, Lauro, John wrote: > > > I did more testing, and it appears that snapshots in LVM will not > work > > > with either 4GB or or 64GB support enabled in the kernel under > 2.4.20. > > > 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? No. This is based on our test results. I reported the highmem problem months ago on linux-kernel. > Does this mean I > should avoid LVM completely with HIGHMEM? No. The problem seems to be limited to snapshots. > What if any other problems > should I expect with LVM (and/or other software)? Any that we and the maintainers of other software are not aware of ;) > > > > Is there anyone using LVM snapshots with 64GB RAM support (or even > 4GB > > > RAM support, as snapshots would be good for at least our medium > size > > > servers if not our large ones)? Is so, let me know the kernel > version > > > and LVM version you are using so that I can try it. > > > > Probably not, because the system lifelocks on bounce buffers (which > is > > the sympton of the principle HIGHMEM bug). > > Obviously not a lot of HIGHMEM users out there raising priorities to > fix > > 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? > > Thanks. > > > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.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 *** =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Sistina Software Inc. Senior Consultant/Developer Am Sonnenhang 11 56242 Marienrachdorf Germany Mauelshagen@Sistina.com +49 2626 141200 FAX 924446 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-