Date: Wed, 18 Dec 2002 14:20:02 -0700 (MST) From: "Geoffrey T. Falk" <gtf@cirp.org> To: current@freebsd.org Subject: Re: Data corruption in soft updates? Message-ID: <200212182120.gBILK2nw002411@h24-67-76-240.cg.shawcable.net> In-Reply-To: <200212172034.gBHKY159017983@beastie.mckusick.com>
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I've run into similar problems dual-booting 4.x and 5.x. Is there some utility one can use to synchronize this once and for all? IMHO, when the UFS1 superblock was changed, it should have been named something else like UFS1_1 to avoid confusion. gtf -- Geoffrey T. Falk, BSc, MA, SCJ2P, SCSSadm7, FreeBSD since 1998 On 17 Dec, Kirk McKusick wrote: > Please send me a `dumpfs /usr | head -50' output of the filesystem > under the current system. Then clean it up with fsck and run the > same command again. Finally, boot up under the old kernel and > get the output both before and after fsck cleaning. What I am > looking for is changes in the reported size of the filesystem > because that getting out of sync is what is causing these problems. > The basic deal is that the old UFS1 superblock stored the filesystem > size in a 32-bit field. The new UFS1 superblock stores the filesystem > size in a new (previously unused) 64-bit field. When you mount a > UFS1 filesystem on a new kernel, it copies the 32-bit size field > to the 64-bit field. At that point the filesystem size is in both > places and should work equally well on old or new kernels. However, > it does not update the 64-bit size field on any of the alternate > superblocks. So, somehow, your using and copying an alternate into > the standard location is losing the update done for the size field. > I am not sure how that is happening, but I am hoping to catch > where in all your messing around with alternates that is happening > so I can cover that hole. > > Kirk McKusick To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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