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» VIEW ALL POSTS Apr 9 2007   7:02AM GMT

Triple whammy, not enough



Posted by: mwright16
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Storage backup

Like many in the storage industry, I keep wanting to declare tape is dead, or at least on its last legs, when it comes to data protection. I surely thought the triple whammy of emerging technologies like deduplication, asynchronous replication and removable disk cartridges were going to finally drive the nail through the heart of tape.

I couldn’t be more wrong. Last week, I had an insightful conversation with the president of a records management firm based in New Jersey which has, for years, serviced high-end customers like financial services and pharmaceutical firms in the Northeast. They also anticipated more of their clients replicating data to them and, for years, reserved space on their floor for disk for this purpose. Instead, they are installing more racks to hold tape and don’t foresee disk happening at all or not nearly to the scope they foresaw years ago.

They are finding that even though clients want or do replicate data, they also find users on the high end of the spectrum want control of the data in its useable format. Once replicated, users spin it off to tape and store it long term with them for long term archival and data recovery under potentially catastropic circumstances. They want the records management company to know as little about the data they are sending them as possible, and they want the data stored in a format inaccessable to anyone but the user. This is a trend that bears watching in the tape market for even as disk cartridge, deduplication and replication technologies take off, new reasons to keep data on tape are emerging.

9  Comments on this Post

 
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  • mwright16
    Tape, as an archival format, will probably never die. The cost to keep PB or even TB of disk spinning will eventually exceed the value of the data itself. Tape lets us offset the value of the data with the cost of keeping it around. Removable cartridges currently can't compete with common tape formats, in terms of $/GB. A $50 LTO-3 cartridge is only 12 cents per GB native, 6 cents per GB with compression. I can't find that economy of scale with any of the current removable disk solutions.
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  • mwright16
    Should I also mention that removable carts are fragile, mechanical devices? You only know if a disk is bad when you spin it up, which often leads to failure, for drives that are not spinning. If you're verifying your backups to tape, you should be comfortable that you can recover from your tapes. If you aren't verifying your backups to tape, you're not doing backups "right", i.e., staging to disk or VTL for speed, then writing slowly to tape with verification.
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  • mwright16
    I work for Idealstor and we have been selling removable disk solutions for the last 4 years. Removable disk is positioned as an alternative to tape backup - not archival. A true removable disk solution lets users decide how to archive their data if it is a requirement (I say this because most companies don't archive their data). We recommend that users use our disks for their daily/weekly/monthly backups. If a user needs to archive, we let them choose between disk or tape. Quick question: Do you really think that most companies will have an LTO-3 drive available in 20 years to recover their archived data? The reality of the situation is, people move to disk because of the reliability and speed of tape backup and restore. Not to mention, companies grow tired of always having to upgrade to a new drive format as their data increases. It is a convenient business model for tape manufacturers but is extremely inconvenient for real world users.
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  • mwright16
    Regarding Ben's comment about whether or not users will have an LTO3 drive 20 years down the line, clearly they won't, but I would bet that they will have switched their disk technologies also, quite a few times over the next 20 years. Migration from one media platform to another is something we have learned to live with over the last 40 years, and will continue to do so. Fortunately, today's backup management software generally provide relatively good tools for handling it.
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  • mwright16
    While there may always be a place for enterprise tape, removable disk technology has some serious advantages that should be considered by every SMB. Excluding $/GB, removable disks are simply better than tape drives, specifically devices like DAT, in several areas: price/preformance, ease-of-use, data interchage, reliability, manageability, investment protection, etc.
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  • Bulent
    I should ask; what is the power consumption of a spinning disk vs. a tape cartridge sitting in the shelf ?. Tape is definitely the most cost effective solution in all means. One other point is; tape is faster! Data streaming performance of disk is still lagging against tape. This is the type of performance you would need in bulk backup/restore operations.
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  • mwright16
    No alleged advantage above of tape cannot be duplicated by approaches such as Copan's "MAID" - which also have far greater overall bandwidth than tape (for that matter, it's hardly clear that tape enjoys all that much bandwidth advantage even on a per-device basis, but given the number of devices in a MAID vs. the number of tape drives one can economically drive in parallel there's on competition at all when it comes to *aggregate* bandwidth) and offer far faster random access (ten seconds or so worst-case to spin up a disk vs. however long it may take to reach desired data on a tape - leaving aside mount/dismount overhead). Not to mention the relative rates of decline in $/GB: while it was admittedly on sale, I paid only $0.125/GB for my most recent disk - with no need to purchase an additional expensive mechanism to load it into. Furthermore, *marginal* space on disk can be very close to free: when normal system activity requires the performance of N disk arms but only a small fraction of N disks'-worth of space, the remaining space on the disks can be used for 'cold' (e.g., backup/archival) data (at least as long as the server is sufficiently reliable to mix such data with production data - I certainly wouldn't advise doing so with DAS on most application servers, but for NAS or reliably-zoned SAN data it should be feasible). Couple inexpensive disks with inexpensive multi-parity-based redundancy that can tolerate the loss of arbitrary numbers of disks without losing data at minimal incremental cost, and tape won't be able to compete on either absolute cost (do you really want to parity-protect across tapes rather than mirror them?) or reliability. The single advantage that tapes retain over fixed-disk installations like MAID is portability, but even that is a double-edged sword (since it also makes them easier to misplace or steal). Enterprise IT conservatism and the leisurely pace of industry innovation are tape's main remaining strengths, and they're visibly evaporating as we speak.
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  • mwright16
    Just to make one point clear (sorry I forgot to above): there's no significant obstacle to using encryption to protect on-disk data at a replication site (Scale 8 did some interesting work in this area IIRC): once again, it's mostly the inadequate pace of industry innovation getting in the way here, not the technology itself.
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  • mwright16
    There is a multiplicity of factors in the disk vs tape equation, not the least being cost e.g. power consumption, data centre space, portability etc. Whilst disk manufacturers are salivating at the prospect of customers storing all of their data on disk, it is difficult to see, in spite of their hype, widespread adoption of disk archive in the enterprise and top end of the SMB market segments. I have no doubt that there is a place for innovators such as Copan, but their technology will not be leveraged for "deep archive" that needs to meet regulatory requirements. There is no doubt that MAID, VTL and deduplication technologies have put a new "spin" (or lack thereof) on archival alternatives. However, whichever way you cut it, disk remains more expensive than tape, and the impending launch of LTO-4 will no doubt offer further cost savings over disk.
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