From owner-freebsd-arch Thu Nov 2 13:35:20 2000 Delivered-To: freebsd-arch@freebsd.org Received: from earth.backplane.com (placeholder-dcat-1076843399.broadbandoffice.net [64.47.83.135]) by hub.freebsd.org (Postfix) with ESMTP id 64BC537B6E4 for ; Thu, 2 Nov 2000 13:35:17 -0800 (PST) Received: (from dillon@localhost) by earth.backplane.com (8.11.1/8.9.3) id eA2LZA740940; Thu, 2 Nov 2000 13:35:10 -0800 (PST) (envelope-from dillon) Date: Thu, 2 Nov 2000 13:35:10 -0800 (PST) From: Matt Dillon Message-Id: <200011022135.eA2LZA740940@earth.backplane.com> To: Alfred Perlstein Cc: Marius Bendiksen , Randell Jesup , arch@FreeBSD.ORG Subject: Re: Like to commit my diskprep References: <200011021725.eA2HPeM38718@earth.backplane.com> <20001102132140.W20567@fw.wintelcom.net> Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG : :* Marius Bendiksen [001102 13:19] wrote: :> > Not to mention the bytes/inode (-i) If you want fsck to go fast on a :> > big filesystem, reducing the number of inodes helps a lot. I find myself :> > using -i 32768 or -i 65536 or even higher numbers on partitions which :> > hold big database files. :> :> FFS is woefully inadequate at handling databases, due to the block :> indirection, but e.g. Oracle will allow you to run directly on top :> of a device. : :Block indirection could be optimized by attempting to allocate :indirect blocks in the same area as either the inode or datablocks :that the indirect blocks address. Indirect blocks aren't relevant if you are using a large block size, because there are few enough of them the OS has no problem caching them. Consider a 32 GB table file: BlockSize Bytes required to store leaf indirect blocks for a 32GB file --------------- ----- 8K blocks size 16MB 32K block size 4MB calculation: filesize / blocksize * 4 = # of bytes worth of leaf indirect blocks required to reference the file. (higher level indirect blocks are inconsequential) It becomes somewhat more of an issue for a terrabyte-sized database, but still no biggy considering the memory you can get these days. A raw device will still be better, but not by much. -Matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message