can you guess? wrote: > This is a bit weird: I just wrote the following response to a dd-b post that > now seems to have disappeared from the thread. Just in case that's a > temporary aberration, I'll submit it anyway as a new post. >
Strange things certainly happen here now and then. The post you're replying to is one I definitely did send in. Could I have messed up and sent it just to you, thus causing confusion when you read it, deleted it, remembered it as in the group rather than direct? >> can you guess? wrote: >> >>> Ah - thanks to both of you. My own knowledge of >>> >> video format internals is so limited that I assumed >> most people here would be at least equally familiar >> with the notion that a flipped bit or two in a video >> would hardly qualify as any kind of disaster (or >> often even as being noticeable, unless one were >> searching for it, in the case of commercial-quality >> video). >> >> But also, you're thinking like a consumer, >> > > Well, yes - since that's the context of my comment to which you originally > responded. Did you manage to miss that, even after I repeated it above in the > post to which you're responding *this* time? > I'm a professional computer engineer, but not a professional photographer or archivist. Long before I got involved in computer archiving issues, I was concerned with "archival processing" of my film and prints, so they'd last a long long time. This was generally a big issue in the photo community, *more* among artists and amateurs than among professionals (the pros mostly cared about getting the assignment done and moving on). Similarly, historical sites like fanac.org (documenting some of the history of science-fiction fandom) are run by amateurs, not professionals. "Consumer" might cut across the set of people who do things with computers differently, I don't know. I'd consider the fanac.org project a consumer use, in the sense that it's not supported by either business income or a big foundation grant, doesn't have paid staff or a budget for much beyond hosting and some backups, etc. But you may be using a more precise meaning of "consumer". Backing off slightly, my point is that lots of people who are not professionally trained or legally or economically required for their business to worry about archiving issues a lot choose to do so anyway. I'm sure you've seen friends messing with old family pictures and being very pleased to have them; you may well have done it yourself. (On the computer, physically, whichever.) I don't see the world as a set of sharply-delineated disjoint categories; if you do, we're going to have trouble reaching any sort of meeting of minds, maybe even communicating at all. > not like > >> an archivist. A bit >> lost in an achival video *is* a disaster, or at least >> a serious degradation. >> > > Or not, unless you're really, really obsessive-compulsive about it - > certainly *far* beyond the point of being reasonably characterized as a > 'consumer'. > I disagree; lots of people are quite careful about some parts of their history -- old letters, family photos, videos of the kids, or all of them. Some people aren't very careful and don't mind if they slip away. But the ones who *do* care a lot aren't that rare, I don't believe. Or it could be other things -- the history of their town, their school, their family, their company, whatever. > ... > > And since the CERN study seems > >> to suggest that the vast majority of errors likely to >> be encountered at this level of incidence (and which >> could be caught by ZFS) are *detectable* errors, >> they'll (in the unlikely event that you encounter >> them at all) typically only result in requiring use >> of a RAID (or backup) copy (surely >> >>> one wouldn't be entrusting data of any real value >>> >> to a single disk). >> >> They'll only be detected when the files are *read*; >> ZFS has the "scrub" >> concept, but most RAID systems don't, >> > > Perhaps you're just not very familiar with other systems, David. > > For example, see > http://gentoo-wiki.com/HOWTO_Gentoo_Install_on_Software_RAID#Data_Scrubbing, > where it tells you how to run a software RAID scrub manually (or presumably > in a cron job if it can't be configured to be more automatic). Or a variety > of Adaptec RAID cards which support two different forms of scanning/fixup > which presumably could also be scheduled externally if an internal scheduling > mechanism is not included). I seriously doubt that these are the only such > facilities out there: they're just ones I happen to be able to cite with > minimal effort. > Okay, it's good those are there too. > ... > > >>> So I see no reason to change my suggestion that >>> >> consumers just won't notice the level of increased >> reliability that ZFS offers in this area: not only >> would the difference be nearly invisible even if the >> systems they ran on were otherwise perfect, but in >> the real world consumers have other reliability >> issues to worry about that occur multiple orders of >> magnitude more frequently than the kinds that ZFS >> protects against. >> >> And yet I know many people who have lost data in ways >> that ZFS would >> have prevented. >> > > Specifics would be helpful here. How many? Can they reasonably be > characterized as consumers (I'll remind you once more: *that's* the subject > to which your comments purport to be responding)? Can the data loss > reasonably be characterized as significant (to 'consumers')? Were the causes > hardware problems that could reasonably have been avoided ('bad cables' might > translate to 'improperly inserted, overly long, or severely kinked cables', > for example - and such a poorly-constructed system will tend to have other > problems that ZFS cannot address)? > "Reasonably avoided" is irrelevant; they *weren't* avoided. And most people (including me) have not the slightest clue how to go about telling "good cables" from "bad cables" other than avoiding obviously-damaged ones and not buying from the peg that's 1/3 the cost of all the other pegs (by examination; I could propose a set of tests to eventually tell the difference). (And that cheap peg *might* actually be just fine, I'm just a bit paranoid about exceptional pricing.) Nearly everybody I can think of who's used a computer for more than a couple of years has stories of stuff they've lost. I knew a lot of people who lost their entire hard drive at one point or other especially in the 1985-1995 timeframe. The people were quite upset by the loss; I'm not going to accept somebody else deciding it's "not significant". Writers faced this problem a lot. I'd classify that as a "consumer" use, but not an amateur one. Their computers are being bought by them at retail, not provided by a corporation and maintained by an IT department. It turns out, most people's lives are fairly important to them. When people start having a lot of their life on their computer, it starts becoming important to them not to lose it. -- David Dyer-Bennet, [EMAIL PROTECTED]; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
