Magnetic storage tape has’t been the recommended destination for the initial back-up copy of data for quite some time, and the question is whether LTO-9, the latest tape open standard, and other market dynamics will changed that.
Here's a look at modern tape drives, discussion of the degree to which ransomware changes the equation, and a closer look at LTO-9.
Tape drives: Too fast for their own good?
In the 80s and early 90s, there was almost a perfect match between the speed of tape drives and the speed of the back-up infrastructure. The back-up drives were capable of writing at roughly the same speed that the back-up system could send.
Then tape drives got much, much faster. Released just a few months ago, LTO-9 at 400MBps is 20 times faster than LTO-1, which was released in 2000.
The filesystems and databases that back-up systems are backing up have also gotten much bigger. This means that while the storage devices holding information have gotten faster, the incremental back-up of the data has not. The back-up system spends the bulk of its time trying to figure out what should be in the incremental back-up instead of actually transferring it.
It might be possible to perform full back-ups at speeds fast enough to make a modern tape drive happy, but most back-ups are incremental and too slow to satisfy the tape drives. Back-up software vendors have responded with features like multiplexing, which interleaves multiple back-up streams into one.
This can be fast enough to satisfy a tape drive, but multiplexing creates other problems. During a large restore, all the data must be read and most of it thrown away because the data being sought is intermixed with back-ups that aren’t needed.
This is why in the last 10 or 15 years most organisations have moved off of tape as a primary back-up, and if they do use tape, they back-up to disk first, then copy to tape. Some companies still use tape for their off-site copy, but even that has become less common as deduplication systems and cloud back-up have continued to lower the cost of using disk.
Most companies using tape today use it for long-term storage and active archive systems where infrequently accessed data is automatically moved out to tape, and automatically brought back if someone requests it. Since tape is much better than disk at holding onto data for long periods of time, this is a good use case for tape.
Ransomware’s threat to back-up
Tape is also a viable option for protecting data from ransomware attacks that specifically target back-ups and that in some cases actually make sure the back-ups are deleted before they ever notify a business of the attack. Backing up to tape and shipping a copy to a vaulting vendor creates a true air gap that ransomware cannot cross.
One downside to tape is that, unlike disk and cloud back-ups, users can't simply launch recovery environment directly from the back-up; that requires random access that tape can’t provide. So a recovery from tape will likely take much longer than a recovery from a replicated disk system, but at least it will not get infected by ransomware.
For example, Spectra Logic, a maker of large tape libraries, was hit by ransomware and used air-gapped tape to recover. That took a while partly because the hardest part was not the actual recovery but figuring out what data on the production network had been infected and so needed to be recovered. The company was determined not to pay the ransom, and it met that goal.
The lure of cloud
Most companies are moving some or all of their computing environment to the cloud. While there is plenty of tape inside every major cloud provider, it's not made available for direct customer use, so tape really isn't a cloud option for corporate customers. This more than anything may mean the final death of tape when it comes to back-up and recovery.
The LTO Consortium seems to know that tapes that keep getting faster are the main reason many organisations have moved away from it as a primary back-up medium. Users can see this if they look at the stats for LTO-9 vs LTO-8.
While LTO-9 is 50 per cent larger (18TB versus 12TB, uncompressed), it's only 11 per cent faster (400MBps versus 360MBps). Compare this with the 20 per cent speed increase of LTO-8 over LTO-7 and the 87 per cent increase of LTO-7 over LTO-6. It is clear that the consortium knows it needs to increase tape’s capacity without making it much faster.
LTO-9’s speed of 400MBps uncompressed and more than 1000MBps compressed is still way faster than any incremental back-up. What these stats do say, however, is that tape vendors are trying to solve the issues that caused the mis-match in speed between back-up sources and tape.
Given that time to restore data is a business-critical metric, it makes sense to use disk or cloud or both as the primary DR mechanism. But also consider using tape to create an air-gapped copy to specifically protect the business from ransomware and think of it as the doomsday copy. Even the slowest recovery from tape is better than a deleted copy on disk.