From owner-freebsd-questions Thu Aug 24 22: 0:30 2000 Delivered-To: freebsd-questions@freebsd.org Received: from wantadilla.lemis.com (wantadilla.lemis.com [192.109.197.80]) by hub.freebsd.org (Postfix) with ESMTP id 50E4037B424 for ; Thu, 24 Aug 2000 22:00:23 -0700 (PDT) Received: (from grog@localhost) by wantadilla.lemis.com (8.9.3/8.9.3) id OAA30200; Fri, 25 Aug 2000 14:30:09 +0930 (CST) (envelope-from grog) Date: Fri, 25 Aug 2000 14:30:09 +0930 From: Greg Lehey To: K H Tan Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Re-partioning hard disk Message-ID: <20000825143009.N39208@wantadilla.lemis.com> References: <39A5FA47.B5620A41@pop.jaring.my> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.4i In-Reply-To: <39A5FA47.B5620A41@pop.jaring.my>; from netline@pop.jaring.my on Fri, Aug 25, 2000 at 12:47:04PM +0800 Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-418-838-708 WWW-Home-Page: http://www.lemis.com/~grog X-PGP-Fingerprint: 6B 7B C3 8C 61 CD 54 AF 13 24 52 F8 6D A4 95 EF Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Friday, 25 August 2000 at 12:47:04 +0800, K H Tan wrote: > Hello, > > I've some questions : > > 1) I've decided to re-partition my hard disk, to allocate more space to > /var for e.g. Is there a way to do this or do I have to reinstall the > whole OS? There are ways, but it might be easier just to reinstall. While you're at it, take a look at my new recommendation on partitioning, attached, from the upcoming fourth edition of "The Complete FreeBSD" > 2) Currently I have one NIC installed. If I install another one and > connect both to a switching hub, will I get double bandwidth? No. > How do I go about making the NICs redundant - in case one fails, the > other takes over? We don't have any mechanism for that at the moment. Greg What size partitions? _____________________ In our example, we have 20 GB of space to divide up. How should we do it? You don't have to worry about this issue, since sysinstall will do it for you if you ask it, but we'll see below why this might not be the best choice. In this section we'll consider how UNIX file systems have changed over the years, and we'll look at the issues in file system layout nowadays. When UNIX was young, disks were tiny. By the time of the Third Edition of UNIX, in 1972, the system disk was a Digital RF-11, a fixed head disk with 512 kB. It was no longer possible to keep the entire system on this disk, so a second file system became essential. It was mounted on a Digital RK03 with 2 MB of storage. To quote from a paper published in the Communications of the ACM in July 1974: In our installation, for example, the root directory resides on the fixed-head disk, and the large disk drive, which contains user's files, is mounted by the system initialization program... As time went on, UNIX got bigger, but so did the disks. By the early 80s, disks were large enough to put / and /usr on the same disk, and it would have been possible to merge / and /usr, but they didn't. Since that time, an additional file system, /var, has come into common use for frequently changed data. This is what sysinstall does by default: [Omitting PostScript image images/disk-label-default.ps 4i ] Figure 6-12: Default disk partition sizes It's relatively simple to estimate the size of the root file system, and sysinstall's value of 50 MB is fine. But what about /var? 20 MB isn't worth the trouble any more. In fact, both file systems put together would be lost in the 19 GB of /usr file system. Why do we still do things this way? Let's look at the advantages and disadvantages: o If you write to a file system, a system crash can have serious consequences for the data integrity of that file system. o If you have a crash and lose the root file system, recovery can be difficult. o If a file system fills up, it can cause lots of trouble. Most messages about file systems on the FreeBSD-questions mailing list are complaining about file systems filling up. If you have a large number of small file systems, the chances are higher that one will fill up while space remains on another. o In single-user mode, only the root file system is mounted. With the classical layout, this means that the only programs you can run are those in /bin and /sbin. In order to run any other programs, you must first mount the file system on which they are located. o It's nice to keep your personal files separate from the system files. That way you can upgrade a system much more easily. o It's very difficult to calculate the sizes of some file systems. For example, on some systems /var can be very small, maybe only 2 or 3 MB. It's hardly worth making a separate file system for that much data. On the other hand, other systems, such as ftp or web servers, may have a /var system of 50 or 100 GB. How do you choose the correct size for your system? o When doing backups, it's a good idea to be able to get a file system on a single tape. In the early days of UNIX, system crashes were relatively common, and the damage they did to the file systems was relatively serious. Times have changed, and nowadays file system damage is relatively seldom, particularly on file systems that have little activity. On the other hand, disk drives have grown beyond most peoples' wildest expectations. The first edition of this book, only five years ago, showed how to install on a 200 MB drive. The smallest disk drives in current production are 10 GB in size, more than will fit on many tapes. As a result of these considerations, I have changed my recommendations. In earlier editions of this book, I recommended to put a small root file system and a /usr file system on the first (or only) disk on the system. /var was to be a symbolic link to /usr/var. This is still a valid layout, but it has a couple of problems: o In the example we're looking at, /usr is about 19 GB in size. Not many people have backup devices which can write this much data on a single medium. o Many people had difficulty with the symbolic link to /usr/var. As a result, I now recommend: o Make a single root file system of between 2 and 4 GB. o Do not have separate /usr or /var file systems. o Use the rest of the space on disk for a /home file system, as long as it's possible to back it up on a single tape. Otherwise make multiple file systems. /home is the normal directory for user files. This layout allows for easy backup of the file systems, and it also allows for easy upgrading to a new system version: you just need to replace the root file system. It's not perfect, though: on a web server you probably wouldn't want to put /var on the root file system. -- When replying to this message, please copy the original recipients. 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