From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 28 Feb 2001 12:38:37 +0000 From: "Heinz J. Mauelshagen" Subject: Re: [linux-lvm] q: BLOCK_SIZE Message-ID: <20010228123837.H4361@srv.sistina.com> References: <3A9BF392.2E4C3DA5@tls.msk.ru> <200102272025.f1RKPg727605@webber.adilger.net> Mime-Version: 1.0 In-Reply-To: <200102272025.f1RKPg727605@webber.adilger.net>; from adilger@turbolinux.com on Tue, Feb 27, 2001 at 01:25:42PM -0700 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: List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-lvm@sistina.com On Tue, Feb 27, 2001 at 01:25:42PM -0700, Andreas Dilger wrote: > Michael writes: > > Little question that I already posted here a long time ago. > > What drawbacks can suffer if one changes BLOCK_SIZE in > > include/linux/lvm.h from 1024 (or 4096 on S/390) to 512? > > On S/390 it would appear that the DASD block devices have a 4096 > byte sector size. However, on most other systems there is only > a 512 byte sector size, so I don't see any reason there would > be problems with BLOCK_SIZE = 512. > > I think Andrea Arcangeli was complaining about this as well. > > > This is about using lvm with rawio -- on 2.2, rawio wan't > > work with i/o size be not a multiple of blocksize, while > > on 2.4 it works. Or at least this was on Dec-2000. > > Oh yes, this is about 2.2 kernel and lvm-0.9. > > If it works for you at 512 bytes, leave it then. Yep. > Maybe Heinz > will let us know why it is set to 1024 bytes. It is basically an approach to support larger LV sizes than 2T :) Because the Linux kernel supports 2^32 blocks per block minor up to version 2.4, this is one approach (with tradeoffs for sure) to raise that limit. With the 4k block size on S/390 DASD devices this means 16T per LV! Sure: we won't have a satisfying solution before Linux 2.5. > > 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 > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm -- 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 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-