Date: Fri, 19 Feb 1999 13:10:01 +1030 From: Greg Lehey <grog@lemis.com> To: Kent Stewart <kstewart@3-cities.com> Cc: Riccardo Veraldi <riccardo@righi.ml.org>, freebsd-questions@FreeBSD.ORG Subject: Re: HOW to format ? Message-ID: <19990219131001.B22647@lemis.com> In-Reply-To: <36CCCADE.E2A39877@3-cities.com>; from Kent Stewart on Thu, Feb 18, 1999 at 06:22:22PM -0800 References: <Pine.BSF.4.05.9501011021560.649-100000@righi.ml.org> <36CC3F61.91EB4912@3-cities.com> <19990219082520.N14890@lemis.com> <36CCCADE.E2A39877@3-cities.com>
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On Thursday, 18 February 1999 at 18:22:22 -0800, Kent Stewart wrote: > Greg Lehey wrote: >> Formatting involves a whole lot more than writing zeros to the disk. >> It writes the sector headers as well, and the pattern that it writes >> is designed to be relatively difficult to read, so that the >> verification pass can catch flaky sectors. > > My bios'es (Award and Phoenix on 5 different computers) don't support IDE > formating. I had a couple of ancient systems that did but nothing dated > after 1996, which is my oldest bios. The "write zeros" is the menu option > used to start a low level format in the WD utility program. In addition, > WDDiag does a disk scan when it finishes, which can involve mapping > replacement sectors into the sequence and giving you a full set. It is much > more involved than anything provided via the bios. OK, I can't see your BIOS, and it's possible that they don't provide the function, but writing zeros is not formatting. >> You almost never need to reformat a disk. This is a Microsoftism. >> FreeBSD reports disk I/O errors, so you should know when a format is >> needed. > > This part isn't always true from my experience. If I write a FreeBSD MBR to > any of my Western Digital Caviar Drives with SMART, the system will not boot > past the first HD test after finishing counting memory. In order to recover > the drive, I had remove it from the bios and then boot from the floppy. I > could then use WDDiag to low level format the drive using the appropriate > I/O port (0x1f0 or 0x170) and offset. Sure, low-level formatting will remove the MBR. You can also use it for deleting files: it does quite a good job, but it's rather non-specific. In this case, for example, you also removed your FreeBSD partition. To repeat: you almost never need to reformat a disk. In this case you seem to have geometry problems which you could fix by writing a correct MBR and without losing the rest of the data on the disk. > Next, you add the drive back into the bios and boot from the DOS > floppy again. At this point you can "fdisk /mbr" and have a working > drive that will not hang my system. Are you saying that Microsoft's FDISK won't write an MBR unless you first low-level format it? That hasn't been my experience, but it does tend to prove my claim that it's a Microsoftism. In any case, to overwrite the MBR you can use dd and save your file systems. You don't need to format, and formatting is detrimental. Greg -- When replying to this message, please copy the original recipients. For more information, see http://www.lemis.com/questions.html See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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