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Hardware

Linux Backup With DVD Media? 46

Posted by Cliff from the seeking-larger-backup-media dept.
Dan asks: "Our research group just moved into a new lab, and I am in charge of organizing the computer systems. A graduate student half-joked about finding a way to get the lab a DVD burner. At first I thought using DVD for backup would be cumbersome, but then I found a few products designed for backups. I targeted a DVDRAM Jukebox by Powerfile for $4000. While it appears to be a good solution for nightly backups, Powerfile does not support Linux. After searching for topics on Linux support for DVD backup systems, I found an unsupported script that was hacked together. There must be more support out there, right? Has anyone else had experience with using DVD as an automated backup system? It wouldn't be such a good idea to spend $4000 on hardware we couldn't guarantee to work, but it would be sweet to have a jukebox DVD burner running on Linux."
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Linux Backup With DVD Media? More

Linux Backup With DVD Media?

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  • How reliable? (Score:4, Insightful)

    by Bazman ( 4849 ) on Friday October 18, 2002 @08:59AM (#4477630) Journal
    There are lots of reports that DVDs burnt on one box aren't readable/playable in another. Check out articles on www.vcdhelp.com for examples (mainly video-related).

    I burnt some video CDs on different CD-R and CD-RW media and found that some friends' DVD players played some and not others, and some played none, and few played them all. I think there are similar problems with DVD-RW, DVD+RW and DVD-RAM. Its put me off buying a DVD burner for video just yet.

    So, do you want to trust your backups to media that might not be readable on a different model device should your one blow up?

    Baz

    • Re:How reliable? (Score:3, Informative)

      by Covener ( 32114 )
      You have to worry about the actually technology (dvd-rw vs. dvd+rw etc.) and also the filesystem you use.

      Along w/ a few different minor/major revisions of UDF that are out there, compatible 'versions' on different OS's can fail to work mysteriously. I had trouble over the summer w/ OS2 and using the 'newer' mkudffs utility in linux.
    • I have had a Pioneer DVD-RW drive for over a year. I have used various brands of DVD-R's to test compatibility. What I have found is that even the cheapest media is compatible with DVD-ROM drives.

      The troubles on www.vcdhelp.com are all about compatibilty issues with DVD players. So, if you want to put a movie on a DVD, or want to restore your backup through your DVD player, then you have compatibility problems to worry about. If you want to restore the backup with a DVD-ROM drive, then you just need to make sure the data was written properly. Unless you get some crap US made disks (http://store.yahoo.com/cd-recordable-dot-com/), there is seldom a problem.
  • I thought of using DVD's for backups also. The problem I see is that the capacity is way to small, it may work for replacing a DDS-1 drive but for most backups I can't get away without using a DDS3. If you have ever conducted a restore over many tapes (remember 6525 tapes?) you know that if tape 3 out of 5 is bad your screwed.

    That being said, I prefer to use one large tape. On some of my older HP machines I can fit an entire backup on one DDS3, that means no incrementals are needed. How sweet is that?

    • If you have ever conducted a restore over many tapes (remember 6525 tapes?) you know that if tape 3 out of 5 is bad your screwed.

      That's why I use afio instead of tar. bad tapes just affect the files in the bad parts of the tape since each file is compressed individually instead of as one like tar.

  • capacity (Score:5, Interesting)

    by zeugma-amp ( 139862 ) on Friday October 18, 2002 @09:41AM (#4477903) Homepage

    The problem as I see it is that not even DVD has the capacity to back up modern systems. The advances in hard disk capacity are vastly outstripping our ability to reasonably back them up. I have over 20GB of MP3s that I've ripped so I won't have to keep my cd collection handy. This is great, but I'm pretty much out of luck if I want to keep the stuff backed up.

    Sadly, the mismatch between capacity of removable and fixed media seems to have always been the case. Years ago, I gave up trying to do periodic backups to floppy once it took 20 or so of them to do the job. Now, here I am with a CD burner with hundreds of times more capacity than those old floppy disks, and I'm still in the same boat.

    I've looked at tape backup solutions, but find it hard to reconcile myself with spending twice as much (or more) on a tape drive as I did the rest of my system. If there were a decent capacity (20GB+) tape drive to be had for approximately the same price as a CD burner, I'd jump on it, and not brgrudge the costs of the tapes so much if I could reasonably expect to be able to drop a tape in the drive and have what should be essentially a reloadable volume available the next morning.

    For corporate systems, DLTs and a changer is a solution of sorts if your company isn't too cheap to lay out the cash, but those kind of systems are definately not within the average home user's budget.

    I still bite the bullet and do quarterly backups, but it's a major effort, mostly because I haven't found a good backup program that I can get to work for me that doesn't want a tape drive. I kinda wish BRU would introduce a version of their program that would write to CD/DVD.

    My two cents. Let the moderation begin!

    • Only on the cheap end, the newest generation of DLT offer 160GB native (320GB compressed claimed by manufacturers) capacities which is enough to back up even a couple of TB with a reasonable number of tapes.
    • The problem as I see it is that not even DVD has the capacity to back up modern systems. The advances in hard disk capacity are vastly outstripping our ability to reasonably back them up. I have over 20GB of MP3s that I've ripped so I won't have to keep my cd collection handy. This is great, but I'm pretty much out of luck if I want to keep the stuff backed up.

      Fair point, bad example: how haven't you got them backed up if you ripped them from your own (or even friends') CDs in the first place? It's the hard-working audio pirates of the world who have the backup problem :-)
      • Perhaps he doesn't want to spend all that time ripping them again when it would take much less time to restore from cd/tape/magic beans?
  • For $4000 you should be able to get a DAT (DDS3 or DDS4) autoloader (20GB native, 40GB compressed for DDS4)...

  • In the long run, Tapes are still the cheapest solution for backups, in terms of $$/GB of space. Some people opt for putting some of their on-sites into cheap HDD storage, like the DX30 (3TB of IDE disk that emulates a tape library through scsi/fc interfaces), since while it's more expensive per gig, it's also a great deal faster and has nice random access compared to a tape library. However, DVDs are still gonna be slow to burn and slow to randomly access a given DVD out of a library.
    • Which tapes are you talking about?

      I just checked on CDW - correct me if I'm wrong:

      1) DLTs are about $2/GB of native capacity - $30-35 for 15GB.

      2) DDS3s are about $0.85/GB of native capacity - $10 for 12GB.

      3) Ultriums are about $0.80/GB of native capacity - $80 for 100 GB.

      Are my numbers wrong here? Given that some IDE drives are now right at $1/GB, I'm not sure that the tape argument will hold true in the long run.

      • Make sure you consider data retention. We have tapes that are over 20 years old (and drives that still read them!!). How long will a standard HDD that costs $1.00/GB hold the same data? I guess the real calculation for comparison could be:

        Cost/(j*Size+k*Time)

        where j and k are weights that quantify the importance of Size and Time.
        Thoughts?

      • When using off-the-shelf software like I have to at work, the IDE solution is far more expensive. We can't do our policies correctly without having the disks emulate a tape library, the DX30 unit I referred to is 3TB of IDE storage for about $55k list price, which works out to around $18/GB. Cheap IDE drives can be had for $1/GB, but then you've got to come up with a system for using large amounts of IDE disks as a virtual tape system, or get your backup software to natively support emulating tapes to local HDD, one of the two. Or buy the DX30 (linux based last I heard) at $18/GB.

        In any case, the IDE solution generally doesn't offsite well. If you want backups you can ship off, it needs to be removable media.

    • Thanks! I was looking for something like the Quantum DX30 [quantum.com] a few weeks back when two of our DDS drives got jammed and caused us hissy-fits.

      Unfortunately given its size and cost, the DX30 only fills a high-end niche. I'd be perfectly happy with a solution that has 5 40G drives in a RAID5 (i.e 160G) and would cost no more than ~ $3/G (i.e. $500). This would take care of most of our daily backups, but we'd still do weeklies to tape.

      Anyone know of a cheap/small DX30 equivalent?

      Staying on topic, I do use DVD+R at home for archival storage, but they're still not big enough to really be used for regular backup. A full 100 G backup still needs over 20 shiny disks, and swapping them out is a royal pain.

      As others have pointed out it's better than CD-ROM, but we really need larger capacity removable storage for home backup...

      Balam
  • ...apart from the name.
  • Boy, 5 GB doesn't sound like much these days... though I suppose it's plenty enough to back up critical data. Although drives are certainly getting bigger and getting filled up, a lot of that is non-critical cruft and bloated software that can be reinstalled from source. So, maybe 5 GBytes is okay...

    One thing I worry about is the reliability of RW media. How many erase/write transitions can a DVDRW blank take? And how long does it take to "reformat" the medium and to write everything back on again?

    According to the DVD+RW alliance, 2.4x DVD write is 3.32 MBytes/sec. That's faster than 2.5MBytes/sec of DLT, but tape drives erase-and-write at the same time. Supposedly AIT's sustain 4MBytes/sec (but I just looked this up, and I have never used AIT's).

    • AIT? AIT-3 is out, and does 12MBytes/sec ... 100GB/tape.
      Ultrium is out, and does 15MBytes/sec ... 100GB/tape as well.

      And higher speeds can be attained, if you use hw compression on compressable data.

      Of course the latest and greatest will cost your your arm, and maybe your leg too :)
  • use a windows box for the interface and stream the files over the network

  • Backup Edge (Score:3, Informative)

    by benjamindees ( 441808 ) on Friday October 18, 2002 @02:03PM (#4480293) Homepage
    Backup Edge [backupedge.com]

    It's not free, but it's faster than tar (heh, heh) and the Linux support is getting better.

  • I've just started using BackupEdge by microlite. It works on Linux, Caldera Open UNIX, UnixWare, and OpenServer, and writes to tape, CD-R/RW, DVD(+/-)R/RW/RAM on several drives. It seems to write successfully on my SONY DVD+R/RW, though I haven't attempted a restore. (Yeah I know - I'll test it *real* soon ;^)

    The user interface is a terminal screen. It also supports command line operation.

    http://www.microlite.com/

    Capt. Percoloator
  • id like to point out that though a hard drive cost more $/Gb than tape, most people do not develope a library of old daily backups, but rather rotate through the same tapes over and over in a weekly to monthly schedule. Doing this make hard drives cheaper per Gb as the longevity of hard drives significantly reduces the costs versus tapes.

    How many times can you write to a tape before it needs replaced? before the media is stretch so bad it cant reliably hold data?

    hard drives can be written to for many many years when used as a backup device in a hotswap bay.

    DVD and DVD-RAM on the other hand, have a limited number of writes and/or rewrites and mean buying more media on a regular basis. The media is more spendy than tapes but does have the low random access times which is nice.

    FYI, i run a computer service center and i have been recommending hot swap drives for backup to all my customers.

    20Gb drives are resonably cheap and last for the forseable lifetime of the machine being backed up. they are just as convinient as tapes in portability but more reliable. In schools i typically have the super or principal take the backup home with him/her OR lock in in the firesafe.
  • Ask Slashdot: How can I try to bullshit our purchasing department into buying a DVD burner so I can encode my DIVX copies of Sailor Moon and hentai onto DVD?

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