Path: utzoo!mnetor!uunet!mcvax!ukc!stl!scott From: scott@stl.stc.co.uk (Mike Scott) Newsgroups: comp.os.vms Subject: Re: Repairing disks with corrupted index files Message-ID: <613@acer.stl.stc.co.uk> Date: 20 Jan 88 11:53:00 GMT References: <2471@trlsasb.oz> <880109071621.025@CitHex.Caltech.Edu> Reply-To: scott@stl.stc.co.uk (Mike Scott) Organization: STL,Harlow,UK. Lines: 26 In article <880109071621.025@CitHex.Caltech.Edu> carl@CITHEX.CALTECH.EDU (Carl J Lydick) writes: > > > We have an eagle disk with a SI 9900 controller which has had it's index file > > corrupted 4 times in the last 4 months. Has anybody else experienced these > > problems. Is it a software or hardware problem.? > >We've had similar problems. In both cases, it appears to have been a hardware We've also had some nasty problems with a supereagle and QD32 controller (on a uVAX-II/VMS4.5). We were getting corrupted data without any warning apart from the disk write-locking itself. After reformatting the disk and restoring from a backup tape which had the corrupted disk data on it, there were a number of files apparently entered in two directories, one correctly, one wrongly. The symptoms were consistent with the bad block replacement algorithm failing by revectoring a supposed bad block in the index file, then forgetting it had done this. It makes me suspicious of the very idea of automatic bad block replacement, if this sort of thing happens with no warning: at least the old badblk.sys was pretty foolproof. The killer is, I don't even think it was a media problem: I suspect a head amplifier - the reformatting program carefully prints out all the replaced block numbers, and hides the fact that they are all on the same disk head! -- Regards. Mike Scott (scott@stl.stc.co.uk ...uunet!mcvax!ukc!stl!scott) phone +44-279-29531 xtn 3133.