Slashdot Mirror

← Back to Stories (view on slashdot.org)

Ask Slashdot: Personal Tape Drive NAS?

Posted by timothy on from the can-tape-actually-be-that-fast? dept.

New submitter hey_popey writes "I would like to piggyback on a previous Ask Slashdot question. Do you know of any realistic way to use a tape drive solution at home, not as a backup, but as a regular NAS? I would like, for example, to save the torrents of my Linux distributions on it, and at the same time, play the family videos on a computer. It would seem at a first glance that the transfer rates and capacity of Linear Tape-Open (1.5TB, 280MB/s in 2010) and the functionality of LTFS would allow me to do that, but I don't know the details, or whether this would be economically viable."

12 of 268 comments (clear)

  1. Nope. by Sprite_tm · · Score: 5, Informative

    The big disadvantage of tapes is that it has long seek times. Not 'long' as in a few times that of a hard disk, but 'long' as in: can take a full minute to do. Access of multiple files on a normal HD is done by reading a meg of the first file, then seeking to the second file and reading a meg, going back to the first file and reading a meg etc. On a tape drive, even when the seek time is only, say, 10 seconds, you'd get a total throughput of 100K/sec that way. And I'm not even talking about the havoc that using it for storage of torrent files wreaks on it: that's a random-access process if I ever saw one, and the seek times on tape would kill your bandwidth very quickly, and probably your tapes too (because of wear&tear).

    1. Re:Nope. by Sprite_tm · · Score: 5, Insightful

      For playing a movie - maybe. For actually burning a torrent - fair enough... if that is the _only_ thing that happens.

      The point is that multiple accesses is going to delay the drive by a huge amount. If you want to, say, copy that Linux iso to your NAS at the same time as someone is playing a movie, the tape drive is going to have to move between the locations of the two files, which is going to wreck the access times, as I stated. Torrents are worse: you're downloading from / uploading to a bunch of other computers, all wanting to read from or write to a different location in the file. Again, this means moving between locations and the resulting huge access times.

      You may be able to alleviate the process by putting a SSD or HD as cache in between, but I'm not sure if there's off-the-shelf software to do that, and I'm not even sure if that's going to work comfortably. Besides, if you're going to put a SSD or HD in between, why not just use that?

    2. Re:Nope. by Lumpy · · Score: 5, Informative

      Yup a lot of people don't remember linear access. and a minute or two? I remember a 15 minute seek and load time when restoring a file from the end of an archive tape.

      In fact it's faster to download a new distro on a 7mbps DSL line than it is to find it on the tape.

      Now, I have seen with a tape robot cabinet a "infinite" hard drive. 4 hard drives for online storage, they had 4 hard drives for nearline storage, and all the tapes in the cabinet for offline storage. if you accessed the file from online and it was on tape, you would get a winpopup from the server stating that the file is in offline storage and will be spooled up for you. it then would email the person when the file was put back into nearline or online storage storage.

      back in 2002 it was how we had 22Tb of tv commercials, Tv show productions, and video footage available for the video editing suites.

      --
      Do not look at laser with remaining good eye.
    3. Re:Nope. by operagost · · Score: 5, Funny

      The station wagon analogy is an amusing analogy to bring up, because if you're willing to wait for videos to stream off of tape, why not just use your station wagon to go to a video store or Redbox?

      --

      Gamingmuseum.com: Give your 3D accelerator a rest.
  2. begone rational thought by Anonymous Coward · · Score: 5, Insightful

    you're not thinking this through, are you? it's a tape-drive...

    1. Re:begone rational thought by Anonymous Coward · · Score: 5, Funny

      Leave him alone! help me with my RAIF - Redundant Array of Independent Floppies

  3. Re:Seek Time by Anonymous Coward · · Score: 5, Funny

    I agree that a tape solution would not work well for torrent files, however using it to store movies should work well. If you wish to market it, I can suggest a name for it. You could call it a VCR. But whenever you do, do not call it Betamax, I don't think that would sell very well.

  4. Cost vs HDD Solution by thesandbender · · Score: 5, Informative

    The overwhelming issues with latency aside, a 1.5TB (native not compressed) LTO drive will set you back ~1800 USD and you'll need an extra ~100-150 for a SAS controller that can drive it. For that price you can by yourself 24TB of HDD storage (12 x 2TB) with enough money left over for a decent SATA/SAS RAID controller. If you setup a RAID 10 array you'll have 12TB exponentially faster access times and better data security (unless you make copies of every tape).

    1. Re:Cost vs HDD Solution by thesandbender · · Score: 5, Informative

      It's economies of scale, tape has a high cost of entry but a relatively low maintenance cost. A 1.5TB LTO 5 tape costs 40 USD. A 1.5TB drive costs 90 USD. The VM enclave I use for testing at one client has 700TB, to back up that data set with HDD would cost 23,333 USD more than tape (for just the media). That difference alone covers the cost of a tape library. And, most corporations are going to take complete backups once a week with incremental backups during the week. Which means an extra 23,333 a week (HDD vs tape). Scale this out to petabytes of data and HDD's become prohibitively expensive.

      Also, one of the primary reasons to use tape is you can store them offsite for disaster recovery. You can put a box full of tapes in the back of a panel van and drive them down a bumpy gravel road without any big worries, you just can't do that with HDD's with out protective housing.

  5. Re:You cannot by Tx · · Score: 5, Funny

    Forget LTO, I recommend a massive array of Sinclair Microdrives. I mean, if you're going for a silly and impractical tape solution, you might as well push the boat out.

    --
    Oh no... it's the future.
  6. Tapes. Are. Useless. by fraxinus-tree · · Score: 5, Informative

    They are not only useless at home. They are completely useless as a backup solution in the first place. They refuse to read in 95% of their intended usage scenarios, including, but not limited to, incompatible/failed tape drives, missing/obsolete/buggy/outright stupid software, degraded/stretched/torn off tape, mislabeled/misordered media and so on. And then again, they cost $$$$$, because PHB's keep on buying them. And they do, because they like solid-looking stacks of backups. Even if no one prescribing them in the backup plans had ever tried to restore a single file in the last 20 years. Or ever.

    Hard disks are good. They are also good for backups. They are cheap, they sell them in the shop down the street, they work 99.99% of their intended usage scenarios, do very well in every other usage scenario, and they can be easily connected to any computer, just to see what's in.

    1. Re:Tapes. Are. Useless. by Anonymous Coward · · Score: 5, Informative

      They refuse to read in 95% of their intended usage scenarios, including, but not limited to, incompatible/failed tape drives, missing/obsolete/buggy/outright stupid software, degraded/stretched/torn off tape, mislabeled/misordered media and so on. And then again, they cost $$$$$, because PHB's keep on buying them. And they do, because they like solid-looking stacks of backups. Even if no one prescribing them in the backup plans had ever tried to restore a single file in the last 20 years. Or ever.

      Being an enterprise backup engineer, I have to disagree with the bulk of this. We do thousands of tape restores every year, the tape media is extremely reliable, and modern tape is FAAAST. Nothing can do streaming database backups or restores faster than tape, particularly multithreaded - at that point, most servers and network infrastructures don't have enough throughput to keep up with the tape drives.

      Now, Joe Admin at an SMB with hand-labelled tapes (versus barcoded), poorly managed and mismatched tape drives, and poorly planned and tested emergency recovery scenarios is a problem.... but that just means that the person making the technical and purchasing decisions doesn't know how to take advantage of tape properly. If you've got mismatched tape hardware versions, tape drive firmware versions, software problems, etc - well, that's a problem of the person managing the solution. Like any other technical solution, if you're poorly trained on backup solutions, you're going to have a poor implementation. You reap what you sow.

      Disk backup has its place, certainly (and my company leverages it heavily as well), but don't write off tape as useless or a poor technical solution. If you need a database backup restored with the smallest RTO, nothing does it faster than tape.