Network Storage

Does SAN Make Tape Backups Obsolete?

16 comments

Network Storage

Back in the day...Despite what people may assume, tape storage backups still remain in use today. Image Source: NOAA

It’s time to toss tape in favor of SAN for reliable backup and restore solutions. Don’t forget to update your resume on your way out to the dumpster with those tapes. Right?

There’s a lot of buzz these days surrounding the idea that SAN is inexpensive enough to use for backups, obviating the need for those clunky old tape libraries, changing out thousands of tapes per week, hiring staff to manage tape media and transporting tapes to an offsite storage facility. Wouldn’t it be wonderful to rid yourself of the expense and hassle of all that tape? It would, if it were possible. But, it isn’t.

The arguments for replacing tape with SAN are compelling. SAN is fast, prices are dropping, and it is a reliable media type. However, there is one ingredient conspicuously missing from the list: Standard SAN disks aren’t removable. The non-portable nature of SAN disks make it impossible to comply with offsite copy requirements. The requirement for offsite backups stems from practices outlined in the “Data Protection” sections of The Sarbanes-Oxley Act (SOX), The Health Insurance Portability and Accountability Act (HIPPA), and others. Offsite backups are nothing new and have been part of backup strategies since the early days of mainframe computing.

Why Tape is Still Prevalent

Corporations have tried unsuccessfully to ditch tape in favor of other media for years. Optical media was the tape killer of the 1990s but its limited size and somewhat unreliable recovery statistics made it useful only on a small scale.

Even today, tape has two significant advantages over other media: cost and portability. Unfortunately, these two advantages outweigh the more significant (logically speaking) disadvantages of tape media: fragility, replacement rate, failure rate, vulnerability to theft, and unencrypted data storage.

So, what is the answer for companies that want to ditch traditional tape in favor of disk media for backups? The short answer is that you can’t ditch it, at least not at the enterprise level. And, you can be sure that no data center manager responsible for providing backup and restore services to customers, would ever go out on an untested limb to replace tape.

Cost Tradeoffs A Consideration

The long answer is that it is possible, though considerably more expensive, to remove tape from your life. Current technology leverages disk space to which data is moved via a Virtual Tape Library (VTL). VTLs are cost-effective because your current backup software uses the VTL as if it were a physical tape library. They’re also efficient because data is moved to them in blocks instead of streams. Then, once your backup to the VTL completes, it’s offloaded to tape, and backup personnel move the tapes to an offsite location.

Removing tape from the equation involves the use of removable disk media. Portability is a requirement for moving backup media to an offsite location. Fortunately, there is such a hard disk type available for this: SATA. SATA, by definition, is hot-swappable. SATA drives are also inexpensive, though not as inexpensive as tape, they feature high capacities (40GB to 3TB), low cost ($0.05 to $0.07/GB), fast data transfer rates (300Mbps), block transfers, and are very durable.

The major downsides to using these cheap, hot-swappable, full-sized (3.5″) disks is weight (1.4lbs or 636g each), data center power requirements, and heat generation.

What About SSDs?

If you’re thinking that solid state drives (SSDs) are a viable alternative, think again. While SSDs aren’t as weighty (2.5oz or 77g) and don’t generate the heat or gulp power like spinning drives, their price is overwhelming (~$2/GB) and sizes don’t measure up (8GB to 160GB).

Your takeaway for today is that the ancient art of tape management is here to stay for a while longer. How long? Until disk storage prices fall to an affordable level on a large scale. Yes, you’re stuck with tape for now, but as long as you are, your bottom line, your tape, and your face will never be red.

Ken Hess is a technical analyst, author, and consultant. You can see his work at KenHess.com

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16 Comments

  1. RobLL

    I disagree with you on the notion that disk based BURA solutions aren't portable to offsite locations. In a disk based BURA solution portability can be gained by using network replication. This is very advantageous for disk solutions since data can be transported securely with no risk of tape loss/damage. Typically, information is replicated to a DR/offsite location which is more than sufficient for enterprises offsite requirements. In fact, a disk based solution can improve an enterprises business continuity plans due to improved restoration performance which helps meet today's enterprises aggressive recovery point and time objectives. And the most important part of backup is the restoration. Another disadvantage of tape not addressed in this article is drive technology changes every few years. What do you do with all of those old tapes? Convert them to the new media? Or keep an old drive around until the tapes age out or the tape technology isn't supported anymore which then might need conversion. Conversion is very expensive. In a disk based solution, converting is a simple data migration from legacy solution to the new one. To arrive at the appropriate BURA architecture, it requires an analysis of a number of dimensions such as data attributes, retention, rpo, rto, backup windows, data accessibility, and information security. Tape is definitely not going away, but disk based solutions warrant significant attention in today's enterprise architectures as the primary BURA basis.

  2. JeffH0821

    And apparently you have never heard of replication, deduplication, or compression technologies. If you are betting your recovery strategy on the robustness of recalled tapes from offsite - I think YOU should probably update your resume.

  3. AC

    Why would you physically transport anything? Leased fiber allows real time, or near real time) backups to off-site SANs. I haven't used tape for nearly a decade.

  4. Ken Hess

    @JeffH0821 You'll be interested to know that many enterprises use offsite data storage and recovery. Have you ever heard of Iron Mountain? Tape is still the least expensive method for moving as much data as large server farms have to.

  5. NDL

    I haven't used tape in ~ 9 years now. Our D/R test cases ave passed with flying colors. It costs less for a GigE to another datacenter with some gear to replicate to than it does to "man the tapes".

  6. cron jobbed rsync provides mature, robust network backup using OpenSSH. That was easy. You can rotate tapes on the other end if you want but why? If you are using that other OS that has a poor network stack and difficulty installing tools like OpenSSH, you should run it in a VM. That way, you can back up and restore the entire thing as a file. Happy hacking and thanks for digging up that wonderful old data center image. It is so WOPR.

  7. Mark Harrison

    I once worked at a middle-tier service provider. The week I started I arrived to discover that they had somehow managed to "blow up" a SAN. Absolutely totalled. I understand it was human error. SANs are like everything else, not foolproof. Several customers (one of them a major government agency) was without its servers for a whole week. For an encore, the storage team managed to do it a second time the following week. On this occasion, it only took three days to rebuild all the servers. It took less time because of the work done the week before had created some tools to assist. On both occasions teams went without sleep for days and the only thing that saved this service provider was tape. All I can say is never underestimate the power of stupidity! I left a few months later. I quickly realised this organisation was systemically prone to stupidity and I didn't want to tarred with the same brush!

  8. Pranshu

    Being part of a storage team that handles highly critical data of various high value clients I can reiterate the same thing...Tapes are very much alive and kicking, though we use some disk based backup systems also..but still Tapes form the backbone of backups. But now the latest tape technologies do not require us to manually ship the Tapes to offsite, Instead we use Replication technologies that use 1GBPS FICON links to replicate Tapes to a D/R site in a different city in real time. And also the data on tape is always encrypted. and is very easy to handle. Though I am amazed seeing people worried about loss of there important mail, and saying Google cant be trusted coz they still take backup on tapes, and there is also some chatter about cloud being unsafe as all the data is on certain servers..etc..etc I would suggest to spare some thought to this: all your financial data, the money in your accounts, is also all stored on a server, and let me assure you its safe, as its still being backed up on a tape..

  9. zuxel

    Wondering if tape is still viable, about 2, almost 3 years after this original post... hope some one reads this lol SSDs are dropping in price, and maybe most likely will eventually replace both hard drives and tape backup. Unfortunately there is always the ECONOMIC factor, and no matter how cheaper SSDs and HDDs will be, i believe tape is here to stay until SSD and HDD manufacturing will be at the same price as TAPE or equivalent in price? SSD form factor and lightness is a benefit over tape, but still not cheap enough, and HDDs are heavy for offsite storage. In terms of leased lines, they are getting cheaper now that FIOS is around, but not sure how many small to medium business are able to afford leased lines. Any elaborations on my thoughts anyone(alive out there) ? p.s. HDDS are about the same price as tape if not slightly cheaper now 2013~14ish, but they are sure heavier.

  10. TapeGuy

    Let's keep it simple. In the science of backup and DR use the rule of 3. A primary instance of your data. A backup copy of your data. A 2nd backup copy of your data at a different site, on a different media, and preferably offline (more on this later). This is a basic D2D2T backup strategy. I also have to contest this paragraph almost entirely, author states: "Even today, tape has two significant advantages over other media: cost and portability. Unfortunately, these two advantages outweigh the more significant (logically speaking) disadvantages of tape media: fragility, replacement rate, failure rate, vulnerability to theft, and unencrypted data storage." Cost certainly, and for the foreseeable future as the aerial density of data on tape continues to increase 40% CAGR. Portability is no longer really used (accept for some archive). The offsite tape copy is now created over the WAN/wire. The 2nd big advantage of tape is offline, the air gap; the protection against application corruption, hash corruption of disk based VTLs, cyber attacks designed to destroy primary data AND backups (lookup Distribute IT and Las Vegas Sands), and rogue employees. That tape copy is a lot harder to destroy. Fragility and theft are no longer an issue since the tape never leaves the tape library (so to the degree your data center/co-lo is secure). Encryption??? Tape was probably the 1st place data at rest encryption was employed - not worth expounding on. I am not sure what he means by replacement rate, but tape libraries are employed for a decade and longer, drives are probably replaced on a 5 to 7 year cycle (compare to disk @ 3 year?), migrate data just as you would in a disk refresh except as needed in the background, Failure rate? An enterprise-class disk drive is capable of recording about 0.1 PB before an uncorrectable bit error occurs. Recording continuously at a native data rate of 155 MB/sec, each disk drive in an array will experience an uncorrectable bit error event every nine days, resulting in 40 RAID recovery operations per year, per disk! An enterprise class tape drive delivers an uncorrectable bit error rate four orders of magnitude lower, equivalent to recording 1,110 PB at up to 252 MB/s for 165 years before an uncorrectable bit error occurs! We are actually living in the age of the first generation of IT "professionals" where some have a deployed a disk only (usually VTLs) backup strategy. It is simply a matter of time before we see something larger that the Distribute IT cyber attack wipe a larger US Corp. off the map - unable to resume operations. It will remind us all to simply think independly, not the latest IT trend, not what my "trusted" storage vendor says, just using your brain and thinking.