Jan
11

Tape Backup vs Hard Disk Backup: What Does the Future Hold?

Tape Backup vs Hard Disk Backup: What Does the Future Hold?

January 11
By

I was frequenting Spiceworks earlier today and came across a post asking if “tape was legacy”.  I think what they were asking is whether backup to tape is the kind of legacy technology today that we see with VHS—there are still a few out there but the technology is on its way out.  I realize that there are still advantages with tape when it comes to large volume backups and the ability to physically move the backup media to an offsite location.  But even with these advantages it seems that backups to disk (and dare I say to the cloud?) have so many more advantages.

Let’s do a quick comparison of tape and disk storage to consider the advantages of each:

Capacity

“As of 2011, the highest capacity tape cartridges (T10000C) can store 5 TB of uncompressed data” (source Wikipedia), while hard drives have followed Kryder’s law (much like Moore’s law) and doubled areal density every two to four years putting disk drive capacity currently somewhere around 4 TB.  This capacity is comparable to that of tapes.  In addition, newer SSD will have even more capacity than existing disk drives while at the same time offering storage in a smaller and smaller physical size.   Add to this the fact that SSD drives are without the moving parts and power requirements of existing drives and it seems that disk storage will far surpass the capacity benefits of tape storage in the near future.

Speed

Several tape drives I’ve looked at have write speeds approaching 500 MB/s with LTO-5 claiming speeds of 800 MB/s.  The maximum speed of a tape drive depends of course on the limitations imposed by physics on the moving parts and magnetic ribbon.  The same limitations also apply to the spindles and platens of a typical hard disk as they rotate inside the disk enclosure.  A typical 7200 rpm hard drive might have write speeds around 130 MB/s.  However, if we again consider SSD disk drives the typical sequential write speeds are closer to 280 MB/s.  These speeds may not be at the same level as tape; however consider the fact that SSD is a newer technology and speeds are constantly increasing.  Add to this the important point that a tape read/write is a linear process requiring the tape to move to a specific point before data can be written or read while disks allow for immediate read/write functionality and it seems again that hard disks are the long-term winner.

Cost

Call me frugal, but cost is often the most important part of any purchase in my opinion.  All else considered equal, I will purchase the lower cost item every time.  And this is where I think hard disk drives really shine.  Tape storage requires a physical tape drive which can range anywhere from $1,400 to well over $12,000.  The tapes themselves range anywhere from $30 to $90 per tape and these costs add up over time.  Compare this with a 6TB WD drive for $329 on NewEgg and cost pretty much cinches the deal.

Ok, so there you have it.  Three very brief (sometimes read as “not thoroughly researched” or “highly opinionated”) feature comparisons and I think we can say that backup to disk is the clear winner if not today than in the very near future.  There’s a reason for the industry moving away from tape backups and towards disk backups.  All I have left to say is that I hope you found this brief journey down a rabbit hole to be as fun and informative as it was for me to write it.

Cheers!

  • ▾ Comments

    1. bhanuka on

      Why was the Durability not considered in this article? Disk drives are generally warranted for 1-3 years and ends life by 5 years. The risk of bad blocks in disks are higher than tape. and tape life time exceeds 15 years.

    2. Steven Snyder on

      Hello Bhanuka,

      I’m sure there are a few other details I left out besides “durability” in this post. That’s the trouble with blogging, there is always something more we want to say but in order to write interesting (and entertaining?) posts we often have to focus on just a few issues to get our point across.

      That said, I believe that DLT media’s ability to retain data integrity over the long-term is mitigated by other concerns. For example, a media may be durable but no longer commonly used. Let me share a personal experience. I used to store a lot of music on Sony mini discs (MDs). These were basically miniature DVDs that are self-enclosed so they last forever (no scratching) and hold a lot of information. Unfortunately, they’re not common enough today for me to take the time to record music on them any more or to play any of my old music, even though I’m sure I could still play many of my old albums.

      Times change, and unfortunately media types change as well. Think Beta and VHS, 8-track tapes, or even reel to reel magnetic tape on older computers. In this article I wanted to emphasize that the industry seems to be moving away from tape backups and perhaps DLT is becoming another example of a dinosaur technology.

      Another concern I have is that disk technology can in many ways duplicate the “durability” of a tape drive. For example, one advantage of RAID is that it expects bad blocks in disk drives to happen and the technology allows for hot swapping drives that fail in order to maintain data integrity over a long time. Drives don’t fail often enough to affect the redundancy advantages RAID offers which is why many small business considered RAID as a low cost alternative to a more complete backup and recovery implementation.

      At some point any media humanity has ever created will fail. Entropy gradually works its way into our efforts to organize the world around us and either a physical disk, an SSD, a DLT, and even hieroglyphs etched in stone will lose their permanence and fade away into the dust of history.
      Looking at it from this perspective, durability seems to be a minor issue in the broader scheme of data storage. The issues that seem most relevant to data storage seem to be those that impact us in the present. This is why I selected Capacity, Speed, and Cost as the most relevant issues for this article.

      Thank you for your comments. I really do appreciate thought-provoking feedback and questions.

    3. daniel on

      you missed so many important factors. just don’t bother writing an article like this if you don’t provide all the information, its far too dumbed down. you have probably lead astray some poor network/system admin who will choose to back up to disk and sacrifice his companies data retention for cost. you don’t know the cost of the average company to lose recoverable data.

    4. Steven Snyder on

      Hi Daniel,

      Thank you for your comments. Yep, there is so much to talk about with this topic. What information would you like to see in more detail? We’re always looking to talk about the tech that interests our readers as well as what interests us.

      Cheers!

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