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Lost Old Recording

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by jimmie57, Apr 29, 2013.

  1. jimmie57

    jimmie57 Hall Of Fame

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    I had recorded Celine Dionne's , A New Day, about 3 years ago. Every now and then I would watch it.
    I keep from 65 to 90 percent FREE space on my drive.
    Today my recording is gone. I checked the History and it is not in there at all.
    I did a Menu, Reset and checked again. It is just gone.
    I have 2 or 3 more that are about that old and they are still in the Playlist.

    I thought they would stay if I kept plenty of Free space. It appears that was not correct.

    New Subject:
    I do love the DVR. Saturday I was going to watch the Sprint Cup Race. I set it to record.
    Then I watched an hour long recording I had from a couple of days ago.
    Switched to the race and watched it ( fast forward 2 on all commercials ) until I caught up to live TV.
    Watched another hour long show I had recorded and then went back to the race.
    By the time I caught up with live TV the race only had a few more laps to go.

    In 4 hours I watched 6 hours of programming, skipped 2 hours of commercials. Holey Moley.

    One of the things I noticed is that I left the recording of the race once without pausing or stopping it first. To my surprise I did not have to back up the recording. It was right where I left it.
     
  2. jdspencer

    jdspencer Hall Of Fame

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    What model DVR? And did it receive new software just before you lost the recording?
     
  3. TomCat

    TomCat Broadcast Engineer

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    Jimmie, I don't think how much free space you have will have much to do with how safe a particular file might be. Since there is no fragmentation on Linux-based DVRs, there is also then no extents file to get corrupted, which is the chief reason why fuller HDDs on Windows are more susceptible to files becoming corrupted and to fetching the files slower.

    For a DVR, any one file is pretty much like any other, regardless of how many files there might be. The odds of any file on the HDD getting corrupted are about the same regardless of what else might be recorded anywhere else, or whether anything else is recorded at all. And having something stored in location A really does not impact storage location B, other than regarding the actual size of the database, which means it has no real impact. FIles recorded on my DVR have as much affect on files on your DVR as do other files on your DVR. IOW, none.

    So what would be my guess here, is that the database record for that particular show got corrupted and can not link to the media file. When you reboot, the sanity check which audits all files against their database records, will mark that space as available for new recordings, meaning it is effectively erased.

    This can happen if the HDD develops a bad spot, and I would worry about other shows disappearing if that is the cause; you really do not want a bad spot to develop over the top of DB records. It can also just happen spontaneously over time from bit rot, which, incredibly enough, is caused by cosmic rays. No kiddin'. IIRC, a bit can get flipped from one to zero or vice versa about every 10 seconds or so on any HDD, and of course the denser the media, such as on a 2 TB drive, the more susceptible it might be.

    So that is almost as scary as dust mites, another problem that is everywhere all the time but typically never really is severe enough to be problematic. Bottom line, if you have a HDD, bits are getting flipped all the time. And this is something all HDDs are susceptible to; there isn't much that can stop a cosmic ray. But the odds of a relatively important bit or one that does not have error correction backing it up getting flipped, are pretty tiny, so lots of bit rot happens all the time; it just is not typically a problem. At least until the wrong bit gets randomly flipped.

    But it is not a matter of if you will lose a particular recording on a HDD, it is a matter of when. Spinning HDDs are just not a reliable archive medium, and each has a real shelf life. They make a good cache medium, which is what a DVR is supposed to be, but permanent storage is, well, just isn't. The sad part is we are somewhat forced to utilize them to archive our media because as consumers we don't really have a better option.

    So, I double record everything that is important on separate DVRs, and if I have something I need to save, I burn it to a DVDRW+, which is SD but still high quality if coming from HD, and maintains 16:9. Not perfect either, but better than losing something important.
     
  4. jimmie57

    jimmie57 Hall Of Fame

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    Thanks Tomcat.
    I did not have but 1 recorder when this particular show aired back then and I have not seen if replayed since I got my second DVR.
    I can buy the show on the web from Ebay or Amazon.
    I recorded several things last night and today so it is probably written over.
    I was just surprised that it did not show in the History section where the items have been deleted.

    jdspencer
    It was on my HR23 DVR. No new software since 4-9-2013 and I had played it since that date.
     
  5. hdtvfan0001

    hdtvfan0001 DIRECTV A-Team

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    Let's just say that not all the tech advice on this topic posted to date is accurate...and leave it at that.
     
  6. inkahauts

    inkahauts DIRECTV A-Team

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    Until I'm headed to the space station or mars, I'll not worry to much about cosmic rays and them causing bit flipping, since they are almost all the blocked before reaching us by our atmosphere. :)
     
  7. PokerJoker

    PokerJoker Godfather

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    What exactly do you mean by gone? Is the program still listed but won't play? Or is the listing itself gone? Those are two different issues.

    Did any other recordings go missing at the same time?

    Did you have this show marked as "keep until I delete"? Did it have a little blue circle with a K in it next to the listing.? That would have theoretically made it a bit more difficult to lose.

    I agree that it should not have disappeared with that much free space. But, as someone else stated, DVRs are not really meant for long term storage. They are meant for short term time shifting.
     
  8. Beerstalker

    Beerstalker Hall Of Fame

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    I think it really boils down to this. Either someone deleted the recording on purpose or accident, or your hard drive is starting to go bad.

    You can try restarting the receiver to see if it might just be a glitch, but if the hard drive is going bad that could cause more issues.

    If the hard drive is going bad you will likely start seeing more issues soon, like other shows disappearing, playback stuttering, etc. I would probably recommend trying to watch as much off of that DVR as you can and moving any scheduled recordings to another one soon (concentrate on stuff not available from On-Demand first since you might not be able to get that stuff back as easily).
     
  9. jimmie57

    jimmie57 Hall Of Fame

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    Thanks beerstalker.
    I am the only user here for this DVR and I feel certain I did not delete it.
    I have had this HR23 for a little over 4 years. Most of my recording I just use to record long enough to skip commercials when I watch a show and then delete them. I had that recording saved for myself. The other old ones I have are just to keep the grand daughters occupied until their mother comes to get them when I keep them, which is rare.
    I will pay close attention and watch for possible Hard Drive problems and go from there.
    I might swap the HR24 for the HR23 and make the 24 my main machine. It is not too much trouble to remake the Series Manger list.
     
  10. jimmie57

    jimmie57 Hall Of Fame

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  11. TomCat

    TomCat Broadcast Engineer

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    Some, but not all. And you may be referring to gamma rays, X-rays, alpha rays (which can't go through a sheet of paper), photons and other rays mostly which have no particle mass which are indeed mostly shielded by the atmosphere from reaching the earth's surface, but cosmic rays, also known as atmospheric neutrons, do have mass, and many of them do get through the atmosphere. They are much smaller, but for their equivalent mass they pack the punch of a baseball being thrown at 90 kmph, and since they are subatomic particles can mostly fly right between the molecules of most room-temperature solids, so they are not insignificant when the target is the particular electrical charge of a bit in memory media. And if they are strong enough to penetrate 60 miles of atmosphere, a steel roof or a metal case will not be enough to prevent them from penetrating recording media.

    This is exactly why ECC RAM was developed. And this is fully-supported by pretty much every accredited scientist who has weighed in on the issue in any brief perusal you might do on the internet, although you members of the Flat Earth Society are welcome to scour the internet for as long as you like until you find the one propeller-head who doesn't completely agree.

    Of course that will not matter, because a consensus over-rules that.

    Some of those accredited scientists have even done the math regarding the probability of a bit flip (Google Berke Durak, for just one example), and if one extrapolates that math, that implies that your 2 TB drive will experience a 96% probability of a bit flip approximately every 8 2/3rds minutes, on average. That implies that some cosmic rays are indeed reaching the earth's surface, and regularly. And when they do, bit rot happens.

    What? You guys think I make this stuff up? :righton:
     
    1 person likes this.
  12. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    I had to google this and while you're correct "not all" get stopped, "many" is more like "some".
    Much more of a concern would be the damage to DNA if it was truly "many" instead of "some".

    I'll refrain from commenting where you pull this out of. :nono:
     
  13. peds48

    peds48 DIRECTV A-Team DBSTalk Club

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    !rolling
     
  14. TomCat

    TomCat Broadcast Engineer

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    So you, not all that surprisingly:

    1) Researched this on the internet Good for you!

    2) Discovered that, once again, I was correct, and that you were not

    3) Attempted to make an issue of how many cosmic rays actually reach earth, when it has already been proven that enough reach earth regularly to flip bits regularly, which was what the original point was in the first place, as if the fact that since this doesn't meet your particular narrow interpretation of the term "many" that this somehow invalidates what has already proven to be absolutely true and accepted by consensus of the scientific community

    4) Attempted your usual predictable smokescreen technique of vainly and lamely trying to change the subject in order to further muddy the waters (and how do we know that this isn't exactly what is behind the damage to DNA that comes with aging?)

    5) Made the obvious, predictable, knee-jerk and without question very hilarious joke which might have had some impact except that it would only be relevant if I were wrong, which you freely agree that I was not

    Must have been a big day for you.
     
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  15. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    I don't profess to know so much on so many topics as yourself. I try not to post novelettes that go on so long most end with their eyes getting crossed.

    The general consensus is that error correcting in the drives makes this insignificant.

    While I did come in late, my first post was pointing out that cosmic rays aren't completely blocked.stopped by either the atmosphere, or the magnetosphere.

    There are some particles that travel through the earth, and these have been very hard to detect, but have finally been with detectors in deep mines.

    Keep touting how wonderful you are, and someday you might believe it, but I'll leave others to judge for themselves and I already know your limitations and proved them.
     
  16. georgewells

    georgewells AllStar

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  17. peds48

    peds48 DIRECTV A-Team DBSTalk Club

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    There is no such things a "back up" hard drive for DirecTV DVRs since installing an external drive replaces the internal one.
     
  18. SomeRandomIdiot

    SomeRandomIdiot Godfather

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    There is another option.

    I had a program recorded for reference (some channel that should not have an issue - just do not remember which channel it was exactly - was not PPV or a Premium Movie Channel). All the sudden I noticed that all the sudden it had an expiration date on it about 8 months later. As it was so far down in the list, probably would not have noticed it unless paying close attention.

    Post on this site at the time (you can go back through my posts from last year if so inclined). Peeps made various comment about how I did not need to keep it, etc etc etc. No one was able to explain why after so long all the sudden an expiration date appeared - or how to stop it.

    True to form, on that day the program deleted itself.

    As thus, it does not surprise me that programs recorded in the past all the sudden disappear - especially if they are so buried you miss the expiration notice.

    BTW, this i not caused by a bad hard drive, based on my experience. If part of the program is on a bad sector of the disk, it normally errors out on playback - or jumps over that part. It DOES NOT totally delete the program from the disk without a trace.

    EDIT: Google is your friend:

    http://www.dbstalk.com/topic/198433-ota-recorded-broadcast-expiring-on-921/
     
  19. SomeRandomIdiot

    SomeRandomIdiot Godfather

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    I doubt this is what the poster means, but it IS possible to make a backup of the DirecTV Hard Drive on a linux computer. I do it every few months - just in case. Better than an all out failure.
     
  20. peds48

    peds48 DIRECTV A-Team DBSTalk Club

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    Ya, you can copy a hard drive to be used on the same DVR. in my books this is known as EXPANDING. if you keep a back up, is to be used in another machine where the machine that made the back up failed,
     

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