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Aucbvax.5550 fa.unix-wizards utzoo!decvax!ucbvax!unix-wizards Sat Dec 26 17:50:11 1981

>From decvax!duke!reed!valer@Berkeley Sat Dec 26 17:38:16 1981 To deal with DEC CE's who accuse UNIX of not logging errors well enough, Reed College invented a logging device to record errors. It works by stashing records (generated by variable length argument lists of <BYTECOUNT,ADDRESS> pairs) into clists, which can then be read out of a character special file. The device driver is simple (100 lines) with most of its work dealing with running out of clists at inopportune moments. Our usage is to record the time, device registers, buffer struct, and device buffer struct when disk errors occur. Since most errors are recoverable in the next retry, we can fairly safely then record them back on the disk (and if not, it is no real loss). Thus, the binary data is saved by running cat -u /dev/log >>/usr/adm/diskerror from /etc/rc. When DEC arrives, we pretty-print the binary data providing bit and field definitions of all the structures. As evidence it is quite overwhelming, permitting analysis by track and sector, frequency analysis by time of day, or whatever. Unfortunately, it does not generally tell them how to fix the problem but only forstalls excuses.

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