On Jan 15, 2012, at 8:49 PM, Bob Friesenhahn wrote: > On Sun, 15 Jan 2012, Edward Ned Harvey wrote: >> >> Such failures can happen undetected with or without ECC memory. It's simply >> less likely with ECC. The whole thing about ECC memory... It's just doing >> parity. It's a very weak checksum. If corruption happens in memory, it's > > I am beginning to become worried now. ECC is more than "just doing parity".
It depends. ECC is a very generic term. Most "ECC memory" is SECDED, except for the high-end servers and mainframes. > http://en.wikipedia.org/wiki/Error-correcting_code > http://en.wikipedia.org/wiki/ECC_memory > > There have been enough sequential errors now (a form of corruption) that I > think that you should start doing research prior to posting. I've been collecting a number of ZFS bit error reports (courtesy of fmdump -eV) and I have never seen a single-bit error in a block. The errors appear to be of the overwrite or stuck-at variety that impact multiple bits. This makes sense because most disks already correct up to 8 bytes (or so) per sector. -- richard -- ZFS Performance and Training richard.ell...@richardelling.com +1-760-896-4422
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