On Thu Jan 5 13:26:16 EST 2012, [email protected] wrote: > On Thu, 05 Jan 2012 13:01:52 EST erik quanstrom <[email protected]> > wrote: > > > if you read 1TB, you have 8% chance of a silent bad read > > > sector. More important to worry about that in today's world > > > than optimizing disk space use. > > > > do you have a citation for this? i know if you work out the > > numbers from the BER, this is about what you get, but in > > practice i do not see this 8%. we do pattern writes all the > > time, and i can't recall the last time i saw a "silent" read error. > > Silent == unseen! Do you log RAID errors? Only way to catch them. > > That number is derived purely on an bit error rate (I think > vendors base that on the Reed-Solomon code used). No idea how > "uniformly random" the data (or medium) is in practice. I > thought the "practice" was worse!
i thought your definition of silent was not caught by the on-drive ecc. i think this is not very likely, and we're explicitly checking for this byrunning massive numbers of disks through pattern writes with verification, and don't see it. - erik
