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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!nntp.coast.net!news00.sunet.se!sunic!mn6.swip.net!seunet!news2.swip.net!nike.volvo.se!cyklop.volvo.se!peter From: peter@cyklop.volvo.se (peter hakanson) Newsgroups: comp.unix.bsd.bsdi.misc Subject: Re: Why one should buy parity memory for reliability? Followup-To: comp.unix.bsd.bsdi.misc Date: 26 Sep 1996 16:00:00 GMT Organization: Volvo Corp. Lines: 60 Message-ID: <52e9a0$j7d@nike.volvo.se> References: <32485B0D.41C6@austin.ibm.com> NNTP-Posting-Host: cyklop.volvo.se X-Newsreader: TIN [version 1.2 PL2] I have a question to BSDI : Will BSD/OS catch these parity error interrupts and act intelligent ? And if so, any hardware examples ? And what recovery options are available? (start mumbojumbo) From other platforms i have seen that some u*x will catch parity error on user programs by killing that program, but errors in the kernel is letal. Other platforms (using ECC) might be able to correct the error AND continue the affected operation. But here ECC support is needed. I have even seen machines which map away suspect memory areas, whenever a error occurs. In any case, detected parity errors should be logged (even if recovered), if corrective action (ie replacement of bad memory) should be possible. (end mumbojumbo) Tushar Patel (tpatel@austin.ibm.com) wrote: : Hi, : I was going through the FreeBSD hadbook and one of the things suggested : in the book is buy "parity memory". : I was involve in designing one of the microcontroller for Motorola, : one of the things we left out for the future controller was not : supporting parity (less pin count). The reasoning was, In the normal : condition the error should not happen, if it does then there is : somethings seriouly wrong, like having high temprature or more noise : in the system. So, the bord designer better design the system correcly. : (They had some hard numbers to back the theory and this is just the : brif explanation). : If the Board supports the parity memory and error occurs then in : theory the OS should be notified and the access should be reapeted. : Does FreeBSD support such error conditions? : What happens in the case of the DMA transfer from the DISK to the : memory or from memory to disk, if the memory error occures then : processor is not looking at the data bus, so does that mean that the : DMA master (SCSI controller) will detect the parity error and : retransfer the data? : There is a big difference in the price between the parity and non : parity memory so I am trying to justify the parity memory purchase. : Please make comments. : Thanks, : Tushar -- -- Peter Hakanson VolvoData Dep 2580 phone +46 31 66 74 27