Disk or Tape Backup. Which is best?


The debate between disk and tape is one of the oldest battles in IT.  It’s hard to believe that these two storage methodologies first appeared on the market in the 1950s.  And despite all of the advances in information technology since then, these two media types have managed to evolve and adapt to the world around them and remain equally relevant to this day.  If you’ve been trying to decide between backing up to tape or disk, I hope you’ll find this video useful.  But before we start talking about what type of media is best, let’s talk a bit about your backup process in general.

The decision to go with tape or disk will depend heavily on the backup process that you decide to implement.  A poorly planned backup process will most likely be error-prone, expensive, and inadequate for the needs of your company.  That’s why you need to put together a business impact analysis first so that you can gain a better understanding of how data is used within your organization.  How much data are you backing up, and why?  If you answered, “I’m backing up all of my data because I can’t afford to lose any of it,” then you probably haven’t properly planned for your backups.  As a backup administrator, you have to balance out storage costs, recovery speed, backup windows, legal concerns, data growth, and many other factors.

Minimizing the amount of data you back up won’t just improve the overall backup process, but it will also allow you to be more flexible as requirements change in the future.  Here are a few common scenarios.  Although critical business files such as Word documents need to be backed up, employees might download large video and music files from the Internet which don’t need to be backed up.  If a file hasn’t been accessed in over two years, does it really need to be on the main production server or can it be stored on less expensive media at another location?

If all of the desktops in your organization have the same configuration, you don’t need to create a system image backup for each.  Just a single copy will do.  You can greatly reduce the size of your backup storage by using deduplication to compress the data.  Many types of data, such as cash data or log files, can be deleted without causing any harm to the organization.  As an added bonus to the cost saving and flexibility benefits mentioned above, keeping your backups small will also help maintain faster recovery times and minimal backup windows.

How will this data be secured?  When most of us think about securing our backups, we’re usually only thinking about the security of the physical media device, but it’s much better to think of protection in terms of the data itself.  A common scenario is for companies to store their backup tapes inside of a fire safe, but in the event of a fire, these tapes will melt.  How many copies of your backups will you need?  Some companies keep one copy on site and another at a remote storage facility.  Others will also keep a third copy at an alternate recovery site.

In addition to your incremental backups, do you also need a raw tamper-proof copy of your data to serve as evidence in the event of a lawsuit?  Is your stored data encrypted in case of theft?  And do you need to send your data over the network using an encrypted connection?  Does your backup storage facility provide adequate security measures, such as security guards, video cameras, fire suppression systems, and emergency generators?  After how many years will you delete your historical archives, and how often will you test them for consistency?  These are all important considerations to keep in mind.  And your company might be subject to external regulations which dictate how this data must be handled.

How fast will you need to restore?  Your recovery speed requirements should be outlined as part of your business continuity and disaster recovery plan.  You should also have a clear idea of which revenue-generating activities take priority in an emergency.  This will help you decide things such as what data gets kept on site and which servers require emergency failover facilities and how much data you can afford to lose in an emergency.  These questions might seem like a lot of work, but all of these factors come into play when deciding which backup media is best suited for various parts of your backup and recovery process.

Tape versus disk.  Disk storage has two things going for it right now.  Obviously, its ability to access data randomly makes it incredibly fast and, over recent years, the price of disk storage has fallen dramatically.  In some cases, it can now be considered somewhat price competitive with tape.  But pricing aside, there is one major difference which sets tape and disk storage apart, and that’s stability.  With a disk, you have the storage media locked inside of a box along with a complicated reading and writing mechanism containing many moving parts.  This greatly increases the chances that the disk might break, forever losing your files.

Another problem with disk is that the media itself is very unstable.  Just a single small error on the platter is enough to destroy your stored data.  This is partly why about 1 in 10 hard drives fail every year.  Although technology such as RAID help with this problem, disk is still no match for tape when it comes to long-term stability and retention.  With tape, the reader head is external of the storage media.  This means that there’s nothing to break since the only moving parts are a piece of tape and a plastic box.  And since tape records data in a linear fashion, it’s also much more resilient against data corruption.

A small flaw in the backup tape can usually be repaired.  And in the event that this chunk of data is permanently lost, the rest of the stored data will usually remain intact.  And when it comes to legal compliance, tapes are the media of choice since you can store data using protected write once read many WORM tapes.  These tapes are tamper-proof and well suited for compliance.

The downside of tape is that data can only be accessed in a linear fashion, which makes it much slower than disk.  If there is a specific file that you need from a hard drive, the needle can just jump to that spot and grab it for you.  Compare this with tape where you have to slowly wind from one end to the other until you locate the file you’re looking for.  For this reason, tape is usually best suited to long-term offsite backup storage and disk is best suited to short-term onsite disaster recovery backups.  An effective data protection strategy will carefully combine both methodologies for maximum protection at a minimal cost.

Cost considerations.  Now that you have a better understanding of how disk and tape are different, you can start to get a sense of how these two tools fit into your overall backup strategy.  At this point, you can begin to see why planning is so important.  When putting together a backup plan, budgeting will also play a major role.  As you decide what data to protect and which storage media is best, you must take all of the costs into consideration.  If you need to buy a tape library or backup server, this will represent a substantial initial investment.  Once you’ve made this decision, you’ll be stuck with the sunk cost for a long time.  You have to consider the total cost of ownership of the media itself, including the shipping and storage costs.

A new backup process will add significant maintenance overhead, and the costs associated with these must be taken into account.  Your backup plan might require special backup software licenses and technical assistance from outside consultants.  In the beginning, you’ll need to overspend in order to accommodate for future growth.  Your backup systems will take up space in your data center and this must be financially accounted for since data center space is a very precious commodity.

And you’ll need to buy duplicate servers for business continuity and pay to have these servers hosted at an alternate emergency recovery site.  It’s important that you consider these added costs well in advance and that you make all external stakeholders aware of them as well.  Too often, people simply assume that hard drive space is the only cost associated with corporate data storage.

The cloud alternative.  As you can see, an in-house backup process can involve a lot of extra expenditures, capital investments, and added maintenance.  That’s why early planning is so important.  Once you make a decision, you must commit to it for the long term because it will be difficult to change afterwards.  For companies that want more of a pay-as-you-go and changes-needed approach, the cloud offers some interesting cost saving opportunities that can help simplify your data protection planning.

Here are a few examples.  For the most basic backup scenarios, cloud backup can pay for itself through the elimination of maintenance, licensing, data center space, and storage costs.  Cloud backup can also help with compliance and can serve as a third-party witness to ensure that your archives haven’t been tampered with.  And in the event of an electronic discovery request, cloud providers can give you access to powerful e-discovery servers which can search through your archives much faster than you ever could with in-house systems.

With cloud-based data protection, there are no sunk costs or capital investments.  You only pay for what you need and have the flexibility to adapt as needs change.  Rather than buying duplicate equipment and paying to have it hosted at a remote data center, you can simply rent space through a cloud provider and have them take care of everything for you.  Cloud backup is more resilient than either disk or tape because cloud backup providers make duplicate encrypted copies of your backups, which are hosted at a secondary location.  This way you have backups of the backups of your data securely stored and encrypted.  Cloud backup providers also regularly monitor and test the integrity of your backups, eliminating lots of maintenance from your backup process.

A disk to disk to cloud backup is a maintenance-free way to keep both local and remote copies of your backups on hand for fast recovery and disaster protection without purchasing any new hardware.  For most organizations, cloud backup can be a real cost-saver while also eliminating unnecessary headaches from the backup planning process.  And since cloud backups are fully automated, this will free up more time for your IT staff to focus on more important projects.

Thank you for taking the time to view this presentation.  If you’d like more information about which storage media is best suited to your backup plan, you can contact Storagepipe Solutions at Canadian server backup.

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