On Tue, Apr 24, 2012 at 12:16 AM, Matt Breitbach <matth...@flash.shanje.com>wrote:
> So this is a point of debate that probably deserves being brought to the > floor (probably for the umpteenth time, but indulge me). I've heard from > several people that I'd consider "experts" that once per year scrubbing is > sufficient, once per quarter is _possibly_ excessive, and once a week is > downright overkill. Since scrub thrashes your disk, I'd like to avoid it > if > at all possible. > > My opinion is that it depends on the data. If it's all data at rest, ZFS > can't correct bit-rot if it's not read out on a regular interval. > > My biggest question on this? How often does bit-rot occur on media that > isn't read or written to excessively, but just spinning most of the day and > only has 10-20GB physically read from the spindles daily? We all know as > data ages, it gets accessed less and less frequently. At what point should > you be scrubbing that "old" data every few weeks to make sure a bit or two > hasn't flipped? > > FYI - I personally scrub once per month. Probably overkill for my data, > but > I'm paranoid like that. > > -Matt > > > > -----Original Message----- > > > How often do you normally run a scrub, before this happened? It's > possible they were accumulating for a while but went undetected for > lack of read attempts to the disk. Scrub more often! > > -- > Dan. > > > > Personally unless the dataset is huge and you're using z3, I'd be scrubbing once a week. Even if it's z3, just do a window on Sunday's or something so that you at least make it through the whole dataset at least once a month. There's no reason NOT to scrub that I can think of other than the overhead - which shouldn't matter if you're doing it during off hours. --Tim
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