Physical Tape

The future of physical tape

Chris Mellor over at The Register posted an article discussing Santa Clara Consulting Group’s (SCCG) recent forecast of the physical tape market.  In summary, SCCG’s latest analysis indicates that physical tape sales (both media and drives) decreased 25% in 2009 and 7% in 2008.  Some may suggest that this accelerating decline is a sign that tape is dead.  I respectfully disagree. Tape still plays an important role in data retention and archival and will be used for years to come.

There are some bright points in SCCG forecast.  They suggest that LTO drive revenue will grow at a 2.47% compound annual growth rate (CAGR) through 2014 while tape revenue will decline by a 2.21% CAGR. Clearly they believe that LTO will continue to dominate the market and outperform all other formats.

Backup Physical Tape Restore

LTO-5 and Disk-based Backup

HP recently announced the availability of LTO-5 and they are currently hosting industry luminaries at their HP Storage Day. I received a question on Twitter from John Obeto about LTO-5 and what it means to VTL and wanted to answer it here. Note that I previously blogged about LTO-5.

The challenge with data protection is ensuring that you meet your backup and recovery requirements, and most companies have fixed SLAs. The advent of LTO-5’s larger tape sizes is nice, but tape size is not the problem, the issue is real world performance. Quantum’s LTO-5 specification suggests maximum performance of 140 MB/sec which is an impressive statistic, but in practice few end users achieve this. The challenge is even greater when you think about minimum required transfer rates as discussed in my fallacy of faster tape post

Backup Physical Tape Restore

Tale of the Tape: Musings on IBM’s 35TB Tape Announcement

A recent tweet by Chris Mellor from The Register caught my eye. He highlighted IBM’s recent development of a 35TB tape. Here are four articles on the topic:


FUJIFILM Announcement

The Register Article

A blog post by Robin Harris at ZDnet

My thoughts

It is interesting to see IBM/Fuji driving tape development. With this announcement they have increased native tape capacity over 21x from LTO-5, the newest LTO offering. The dramatic density improvement will drive a continued decrease specification-based $/GB. However it also raises some new questions:


Physical Tape

Musings on the Spectra Logic T-Finity Announcement

Last week Spectra Logic unveiled the T-Finity, a new high-end tape library that is one of the largest and most scalable units in the industry.  The system can grow to 30,000 tape slots and 480 drives and it creates some interesting questions.

As data backup and recovery SLAs have become more stringent, end users have migrated rapidly to disk-based technologies.  Deduplication also adds value by reducing $/GB and required disk capacity although the technology can negatively impact backup and recovery performance.  These two trends have combined to reduce the requirements for physical tape and many tape vendors are seeing declining revenues.  This is not to say that tape is dead, it is very much in use and will be for the foreseeable future, but the use model has changed.  Physical tape is typically used for very long-term data archival where multi-year retention is not uncommon.

Backup D2D Deduplication Restore Virtual Tape

Streaming LTO-5

Chris Mellor (twitter:@Chris_Mellor) recently posted an article over at The Register about LTO-5 entitled Is LTO-5 the last harrah for tape?.  He makes an interesting point about the future of LTO and whether LTO-5 will be the last generation of the technology.  Most of the comments on the article disagree with Chris’s opinion.

I believe that there is another major issue with LTO-5 that must be addressed.  The challenge with LTO (and most other tape technologies) is its limited ability to throttle performance.  Users must carefully manage their environment to ensure that they stream their drives or else backup performance will decline dramatically.  As drives become faster, the challenge of optimizing your environment for the technology becomes more difficult.  You can read more about this in my blog post entitled The Fallacy of Faster Tape.

Backup Deduplication Restore

W. Curtis Preston on physical tape

W. Curtis Preston recently wrote an article on the state of physical tape for SearchDataBackup. He talks about the technologies that backup software vendors have created technology to more effectively stream tape drives. As I posted before, if you cannot stream your tape drives, their performance will decline dramatically.

In enterprise environments, performance is the key driver of data protection. You must ensure that you can backup and recover massive amounts of data in prescribed windows, and tape’s inconsistent performance and complex manageability makes it difficult as a primary backup target. This fact can also make tape a challenging solution in small environments.

The problem with tape drive streaming is a common one and Preston agrees that it is the key reason for adopting disk-based backup technologies. Our customers typically see a dramatic improvement in performance with SEPATON’s VTL solutions since they are no longer limited by the streaming requirements of tape.

Even with new disk and deduplication technologies, most customers are still using tape today and will do so into the future. However, tape will likely be used more for archiving than for secondary storage.  Deduplication enables longer retention, but most customers are probably not going to retain more than a year online. Tape is a good medium for deep archive where you store data for years, but is complex and costly as a target for enterprise backup.

Backup D2D Restore

The Fallacy of Faster Tape

I often talk about disk-based backup and virtual tape libraries (VTL) and wanted to discuss physical tape. While VTLs are popular these days, tape is still in widespread use. LTO tape, the market share leader, continues to highlight increased density and performance. Do not be fooled with these claims. In the real world faster tape often provides little or no improvement in backup and/or restore performance. Ironically, faster tape increases (not decreases) the need for high performance disk devices like VTLs. Let me explain.

Modern tape drives use a linear technology where the tape head is stationary and the tape moves at high speed above it. Through each generation of LTO, the tape speed is largely unchanged while tape density doubles. At the same time, LTO drives have not expanded their ability to vary the speed of tape. Thus if you go from LTO-3 to LTO-4, you have doubled the density of your tape and you must double the throughput of data handled by the drive to keep tape speed unchanged. Why does tape speed matter? Because LTO tapes have a limited ability to throttle tape speeds, your performance will suffer terribly if you cannot meet the drives minimum streaming requirement.

If you are unable to stream enough data to your tape drives as mentioned above, the tape drive will go into a condition called “shoe shining” where it is constantly stopping and starting. It will try to stop when its buffer empties, but the tape is moving so fast that it will overshoot its stopping point and need to slowly stop, rewind to where it stopped writing and begin writing again. The tape moves forward and backward like shoe shine cloth. This process causes a massive reduction in performance and excessive wear on the tape drives and media. The table below comes from a Quantum whitepaper entitled “When to Choose LTO-3” and highlights the real world performance requirements of LTO-2 and LTO-3. I have estimated LTO-4 requirements for completeness.

D2D Deduplication Virtual Tape

Tape is not dead!

I am amazed when I hear some vendors aggressively promote that tape is dead. It seems that hyping the demise of tape is in vogue these days and the reality is quite different. Even so,  there is no stopping them from sharing their message with anyone who will listen. If you ask large enterprises, many of them are looking at alternatives to tape, but telling them that tape is completely dead and that they should rip out all tape hardware is ludicrous. Ironically, this is the approach of some deduplication vendors.  Jon Toigo states this succinctly in his blog.

The problem with tape is that it has become the whipping boy in many IT shops.
Courtesy: Drunken Data

The simple reality is that tape has been an important component of data protection for years and is likely to maintain a role far into the future. The reader should remember that in today’s highly regulated environments, companies often face strict requirements about data retention. For example, medical institutions can face some of the most stringent requirements:

HIPAA’s Privacy Rule, in effect since 2003 or 2004 depending on the size of the organization, requires confidentiality of patient records on paper and sets retention periods for some kinds of medical information, regardless of media. These retention requirements can stretch from birth to 21 years of age for pediatric records, or beyond the lifetime of the patient for other medical records.
Courtesy: Directory M

With this in mind, let’s look at the evolution of tape: