Tape Refuses To Die
With the ever increasing use of disk based backup systems, there is no doubt that disk offers many benefits over tape, not least restore performance and reliability, combined with some great technical advances like deduplication. That said is tape truly dying?
Rarely a week passes when I don’t talk to a customer who wants to reduce their reliance on tape. The primary issue with tape is performance, this is of particular concern when backing up lots of small files, with regard to restore speed and also issues caused by media volatility and drive failures can render tape unreliable.
Disk as a backup technology has been around for many years, however, recently disk has become almost a standard for customers looking for new backup solutions. Disk doesn’t suffer from many of the reliability issues of tape and the cost of network links combined with WAN optimisation and deduplication has meant that data replication is not only a large business luxury and rather every businesses necessity. In addition to this disk is known to be considerably faster than tape for restores, although tape can often outperform all but the fastest disk backups when backing up certain optimum datasets for tape such as extensive databases.
Disk staging is using disks as an additional, temporary stage of backup process before finally storing backup to tape. Backups stay on disk typically for a day or a week, this is so that recovery of small files such as a power point or email can be quickly and easily recovered from disk. Proceeding this short storage period on the secondary disk data is then moved onto tape in a background process and deleted afterwards.
So disk is sounding like the obvious choice right? Well, where disk falls down is simply the cost if a customer needs to keep data for extended periods of time – the current consumer price of an LTO-5 tape is in the region of £17 for 1.5TB of storage capacity which equates to £11.33 per TB (prices may vary). Compare that to disk, where you will likely pay more than £50 for a basic 1TB desktop disk, and you can see the appeal of tape. There are, of course, other costs to both solutions, including drives, enclosures, power, cooling and so on but media alone for media tape offers a significant cost advantage!
Recent analyst studies have shown disk to be anywhere from two to fifteen times more expensive to implement than a tape based solution for long term archive storage and the cost to run and, according to the same study, the cost to run and cool a datacentre could be anything up to 200x more for a disk only solution. Added to that, we are about to see the launch of LTO-7 offering 6.4TB native on a single tape with a roadmap planned to LTO-8 which will offer 12.8TB native on one tape and that delta could continue to get bigger.
See the history of LTO, (Linear tape open) credited from wikipedia: https://en.wikipedia.org/wiki/Linear_Tape-Open
So what’s the conclusion is disk in fact the dying breed? Of course not! Disk’s a great medium for backup and restoration, especially for short term requirements such as email recovery or finding lost spreadsheets.
If your business is only required to keep data for a short time then disk only will be a great option for you. On the other hand, if you need to keep data for longer, then think about using disk combined with a flexible form of deduplication (variable block size) for your short term requirements (email recovery etc) and then move the data off to tape for long term archiving. With this solution, you utilize the strengths of both without the negatives, perfect…