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atomicharri
Asked: 2009-10-23 20:33:09 +0800 CST

Choosing the right backup solution - SCSI vs SATA tape drives

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I'm backing up about 100gb worth of data on backup exec and after much deliberation, have decided that tapes are worth another shot (after my ultrium decided to die and munch tapes). Bearing in mind that my SCSI controller might be on its way out, I'm looking for the most economical solution without sacrificing any quality.

I've been trying to decide between SCSI or SATA for the tape drive. I haven't had much luck finding SATA tape drives but from what I can see, they are approximately the same price for increased reading/writing speeds. It will, however, require me to buy a SATA controller card which may add to the cost. I'm not sure if my SCSI controller is on its way out, but I'm a tad skeptical about its integrity after the drive died (and it's onboard too which means the board may soon follow).

How do SCSI tape drives compare to SATA and is it worth the extra money? And if so, which tape drives (both SCSI and SATA) and what capacity should I be looking at to cover 100gb of data with incremental backups? What version of backup exec should I be looking at getting? I've got 10D installed atm.

windows-server-2003

5 Answers

  1. Avoid SATA tape drives - the only one's I know of take DAT/DDS tapes (which is a horrible format).

    I'd suggest a SAS or SCSI LTO3/LTO4 drive. LTO is effectively the standard tape format.

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  2. I'm going to second NinjaStyle's comment about using disk space for backups.

    Tapes are a terrible medium. The tape drives have a habit of destroying tapes when they kill themselves, the tapes themselves are fragile. Anyone ever have to have a DLT tape repaired from a broken leader?

    You've got three choices -- Older tape drive technology, newer tape drive technology, and disks. Older tape drive technology would be LTO2. Guess what, it's only available in SCSI. Newer tape drives, such as LTO4, are much more expensive and mostly available in SAS. Disks, well, they're disks. Let's run the numbers:

    CASE 1 -- obsolete tape technology:

    Pros:

    • Cheap
    • fast enough,
    • reliable and proven technology
    • 200gb uncompressed capacity

    Cons:

    • 200gb uncompressed capacity
    • You'll have to change tapes yourself
    • Without two tape drives, duplicating backup images will be somewhat clumsy.
    • You'll want a second tape drive anyhow in case one of them breaks.
    • If your backups grow past one tape, you'll be in an world of hurt because you'll need to babysit the tape drive.
    • You'll have a hard time restoring backups without the tape drive (see second concern).

    CASE 2 -- Modern tape technology

    Pros:

    • same as above, but 800gb uncompressed capacity
    • because it is newer, it is less necessary to keep a spare around (ie it won't be discontinued between when you buy it and when you need the spare)

    Cons:

    • the tapes are more expensive. Even though they're larger, sometimes you want two copies of your backups on 2 different media, and the cost of that just went up.

    Case 3 -- JBOD

    Now -- you wouldn't use this as a raid. You would mount each disk and format each disk individually, put individual filesystems on to these disks, and only keep the "active" disks inserted and mounted; the rest would not be plugged in or active in any way. You'll want to make each backup to 2 different disk drives, or at least automate duplicating the backup image from one disk to the other.

    Pros:

    • More online storage
    • faster random access
    • easier to recover without any special gear (no need for a tape drive to recover from any backup)
    • easier to expand -- any new sata disk is compatible with this, no need to stick to the same style of disks originally used.

    Cons:

    • disks don't have the same shelf life as tapes
    • disks are more fragile than tapes
    • disks can be affected by the system more than tapes (think virus infection or rm -rf /)
    • managing the backups is a bit more of a pain in the ass because you have to manage the image duplication your self or buy more expensive software.

    In short -- the question of which interconnect to use is basically chosen for you by which sort of tape drive you use. Otherwise, how you do your backups is a matter of which engineering compromise you're willing to make. When I did backups, I preferred to do them straight to disk, but then I had several SATA <-> FC enclosures and several computers and would duplicate the images between the computers and the enclosures. You're probably not looking at quite the same level of infrastructure to support your backups. I've certainly seen LTO2 robots work very nicely.

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  3. To respond to flopcat, I don't understand your reasoning. Who says I can't do a rotation of 7 HD's just like 7 tapes and do 1 per day?

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  4. If all your backing up is 100GB why bother with tapes? you can buy external USB HDD for the price of an ultrim tape.

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  5. a backup to a hard drive is different then a backup to tape for one reason. you can use multiple tapes. if you get 7 tapes and label them sun to sat. use each one on the day of the week you have 7 backups. if one is bad thre are 6 more to choose from. if your hd backup is bad there is no hope.

    if you accidentally delete or change a file and want the old copy back from 3 days ago your hd backup from yesterday is useless. but my way you can go back 7 days. more if you choose to say keep a copy every month as an archive. you can also easily take a tape off site for backup after a catastrophe such as a fire or flood ruins your computer AND the backup drive attached to it.

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