From owner-freebsd-current Wed Apr 26 23: 6: 3 2000 Delivered-To: freebsd-current@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by hub.freebsd.org (Postfix) with ESMTP id C1BC237B5A0 for ; Wed, 26 Apr 2000 23:06:00 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.3/8.9.1) id XAA00807; Wed, 26 Apr 2000 23:05:59 -0700 (PDT) (envelope-from dillon) Date: Wed, 26 Apr 2000 23:05:59 -0700 (PDT) From: Matthew Dillon Message-Id: <200004270605.XAA00807@apollo.backplane.com> To: "John W. DeBoskey" Cc: freebsd-current@FreeBSD.ORG Subject: Re: Support for large mfs References: <200004270554.BAA34693@bb01f39.unx.sas.com> Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :Hi, : : Today, we tried to create a 5Gig mfs. It turns out this is :not such a good idea. It turns out that support is basically :limited to an int. Extracts from some of the appropriate files :show some of the problems... More then just a few.... MFS uses an mmap()'d segment, so you can't create an MFS partition larger then what a process can mmap() anyway. The max is going to be around 2-3 GB. You should be able to create a large virtual VN device. man vnconfig for more information - you have the choice of making it file-backed, swap-backed, or swap-backed with the swap pre-reserved. file-backed VN devices have a sector size of 512 bytes (which is standard). Swap-backed VN devices have a sector size of a page (4K on PC's). vnconfig up a VN device, disklabel it, and newfs away. You can also turn softupdates on in the VN filesystem partitions. I've tested VN all the way to a terrabyte - and just managed to newfs it before I ran out of swap :-) -Matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message