Date: Sun, 23 Jul 2000 13:30:05 -0700 (PDT) From: John Baldwin <jhb@pike.osd.bsdi.com> To: "Patrick M. Hausen" <hausen@punkt.de> Cc: stable@FreeBSD.ORG Subject: Re: No /boot/loader (dangerously dedicated) Message-ID: <200007232030.NAA23028@pike.osd.bsdi.com> In-Reply-To: <200007231444.QAA94743@hugo10.ka.punkt.de> from "Patrick M. Hausen" at "Jul 23, 2000 04:44:56 pm"
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Patrick M. Hausen wrote: > Hello all! > > Mikhail Teterin wrote: > > > John Baldwin once stated: > > > > ="No, you shouldn't." Some SCSI controllers are _known_ to go haywire > > =with a dangerously dedicated disk since it uses a completely bogus > > =geometry. > > > > Then those need to be explicitly listed and, better yet, identified at > > install time... This is, however, a one shot deal, but you'll be wasting > > those 5Mb forever. > > Personally I don't mind 5 MB wasted space - our production machines > have one GB of swap _just_in_case_ some Godzilla email from hell > hits them or some kiddy tries to DOS our Apache or whatever ... > > But ... Ok, _before_ everyone gets _really_ tweaked and goes off blowing this way up and imagining that things have been said which have _not_ been said: MBR's are not a MS-DOS thing. They are a _PC_ thing. In fact, the IA64 uses the smae MBR structure as well. It is _not_ a Sparc thing, however, which is why Solaris on a Sparc doesn't have it. This is an architecture issue, _not_ an OS issue. *sigh* The new boot0 won't work with dedicated disks. But the old one didn't either. If you will never reformat your disk again, this is not a problem. Of course, since you hose the MBR, some OS's won't be able to figure out what geometry the BIOS is using and won't be able to partition your hard drive properly. (hence the "never reformat again" comment). That said, while having a dedicated mode does result in some hacks in a few places where we have to detect a dedicated disk and create a fake "compatibility" slice for it, I unfortunately don't see it going away just yet. Even if it does go away, we would first take out the ability to create them and then wait a major release before removing support for reading them. This is not unprecedented. To upgrade some of my machines to 4.x I had to repartition and reformat since we don't support bad144 in 4.x and above. I also don't see any code from anyone who is jumping up and down about possibly fixing the few remaining cases where sysinstall may botch the geometry of a disk. At the very least, dangerously dedicated mode should specify a valid length for the slice the way that truly dedicated mode does so that if you ever need to stick a dedicated disk in another computer for some reason, it doesn't see that all but the first 25,000k as being free and happily reformat it for you or other nonsense. > Folks, gemoetries are for brain damaged PC operating systems. > All the box needs to boot is a proper MBR. BIOSes that > don't boot from a dedicated disk are _broken_. No, they are actually smart in that they attempt to use a geometry that matches the MBR so that you can move disks around. As a result, when we try to fake it, it confuses them. > I'm really puzzled by this thread, because after years of running FreeBSD > I've come to the opinion that "dedicated" is how disks should be partitioned > under all circumstances ... I mean, where's the partition table on > my Sparc systems running Solaris? Who would care installing MS OSs > additionally to FreeBSD on a server providing 24x7 service? IA-64 mandates a valid MBR. It boots from a special FAT-32 partition containing the EFI boot loader. Get used to the idea. -- John Baldwin <jhb@bsdi.com> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.cslab.vt.edu/~jobaldwi/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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