Years ago, when I did systems administration for a small company, we used RAID 1 for in-house data redundancy and an LTO tape setup for offsite data backup. Yes, the LTO cataloging and versioning were a pain, so was managing the tapes, and sometimes a tape would be unreadable, but the setup worked. And given there were few affordable alternatives out there at the time you lived and died with your tapes.
Over the last few years, cloud storage has emerged as a viable alternative to using LTO for offsite backups. Improvements in network speed coupled with lower costs are a couple of the factors that have changed the calculus of cloud storage. To see if enough has changed to make cloud storage a viable competitor to LTO, we’ll start by comparing the current and ongoing cost of LTO versus cloud storage and then dig into assumptions underlying the cost model. We’ll finish up by reviewing the pluses and minuses of three potential outcomes: switching to cloud storage, staying with LTO, or using a hybrid LTO/cloud storage solution.
Comparing the Cost of LTO Versus Cloud Storage
Cost calculators for comparing LTO to Cloud Storage have a tendency to be very simple or very complex. The simple ones generally compare hardware and tape costs to cloud storage costs and neglect things like personnel costs, maintenance costs, and so on. In the complex models you might see references to the cost of capital, interest on leasing equipment, depreciation, and the tax implications of buying equipment versus paying for a monthly subscription service.
The Backblaze LTO vs Cloud calculator is somewhere in between. The underlying model takes into account many factors, which we’ll get into in a moment, but if you are a Fortune 500 company with a warehouse full of tape robots, this model is not for you.
To use the Backblaze calculator you enter:
- the amount of Existing Data you have on LTO tape
- the amount of data you expect to add in a given year
- the amount of incremental data you backup each day
Then you can use the slider to compare your total cost from 1 to 10 years. You can run the model as many times as you like under different scenarios.
Assumptions Behind the Model
To see the assumptions that were made in creating the model, start on the LTO Replacement page and scroll down past the LTO vs. B2 calculator. Click on the following text which will display the “Cost and Operational Assumptions” page.
Let’s take a few minutes to review some of the most relevant points and how they affect the cost numbers reported:
- LTO Backup Model: We used the Grandfather-Father-Son (GFS) model. There are several others, but this was the most prevalent. If you use the “Tower of Hanoi” model for example, it uses fewer tapes and would lower the cost of the total LTO cost by some amount.
- Data Compression: We assumed a 2-1 compression ratio for the data stored on the LTO tapes. If your data is principally video or photos, you will most likely not use compression. As such, film studios and post-production houses will need to double the cost of the total LTO solution to compensate for the increased number of tapes, the increased number of LTO tape units, and increased personnel costs.
- Data Retention: We used a 30 day retention period as this is common in the GFS model. If you keep your incremental tapes/data for 2 weeks, then you would lower the number of tapes needed for incremental backups, but you would also lower the amount of incremental data you keep in the cloud storage system.
- Tape Units: There are a wide variety of LTO tape systems. You can increase or decrease the total LTO cost based on the systems you are using. For example, you are considering the purchase of an LTO tape system which reads/writes up to 5 tapes simultaneously. That system is more expensive and has higher maintenance costs, but it also would mean you would have to purchase fewer tape units.
- LTO-8 Tape Units: We used LTO-8 tape units as they are the currently available LTO system most likely to be around in 10 years.
- Tape Migration: We made no provision for migration from an unsupported LTO version to a supported LTO version. During the next 10 years, many users with older LTO systems will find it likely they will have to migrate to newer systems as LTO only supports 2 generations back and is currently offering a new generation every 2 years.
- Pickup Cost: The cost of having your tapes picked up so they are offsite. This cost can vary widely based on geography and service level. Our assumption of the cost is $60 per week or $3,120/year. You can adjust the LTO total cost according to your particular circumstances.
- Network Cost: Using cloud storage requires that you have a reasonable amount of network bandwidth available. The number we used is incremental to your existing monthly cost for bandwidth. Network costs vary widely, so depending on your circumstance you can increase or decrease to the total cost of the cloud storage solution.
- Personnel Cost: This is the total cost of what you are paying someone to manage and operate your LTO system. This raises or lowers the cost of both the LTO and cloud storage solutions at the same rate, so adjusting this number doesn’t affect the comparison, just the total values for each.
- Time Savings Versus LTO: With a cloud storage solution, there are no tapes or tape machines to deal with. This saves a significant amount of time for the person managing the backup process. Increasing this value will increase the cost of the cloud storage solution relative to the LTO solution.
As hinted at earlier, we don’t consider the cost of capital, depreciation, etc. in our calculations. The general model is that a company purchases a number of LTO systems and the cost is spread over a 10 year period. After 10 years a replacement unit is purchased. Other items such as tapes and equipment maintenance are purchased and expensed as needed.
Choosing a Data Backup Model
We noted earlier the three potential outcomes when evaluating LTO versus cloud storage for data backup: switching to cloud storage, staying with LTO, or using a hybrid LTO/cloud storage solution. Here’s a look at each.
Switching to Cloud Storage
After using the calculator you find cloud storage is less expensive for your business or organization versus LTO. You don’t have a large amount of existing data, 100 terabytes for example, and you’d rather get out of the tape business entirely.
Your first challenge is to move your existing data to the cloud — quickly. One solution is the Backblaze B2 Fireball data transfer service. You can move up to 70 TB of data each trip from your location to Backblaze in days. This saves your bandwidth and saves time as well.
As the existing data is being transferred to Backblaze, you’ll want to select a product or service to move your daily generated information to the cloud on a regular basis. Backblaze has a number of integration partners that perform data backup services to Backblaze B2
Staying with LTO
After using the calculator you find cloud storage is less expensive, but you are one of those unlucky companies that can’t get reasonably priced bandwidth in their area. Or perhaps, the new LTO-8 equipment you ordered arrived minutes before you read this blog post. Regardless, you are destined to use LTO for at least a while longer. Tried and true, LTO does work and has the added benefit of making the person who manages the LTO setup nearly indispensable. Still, when you are ready, you can look at moving to the hybrid model described next.
Hybrid LTO/Cloud Storage model
In practice, many organizations that use LTO for backup and archive often store some data in the cloud as well, even if haphazardly. For our purposes, Hybrid LTO/Cloud Storage is defined as one of the following:
- Date Hybrid: All backups and archives from prior to the cut over date remain stored in LTO; everything after the cut over date date forward is stored in cloud storage.
- Classic Hybrid: All of the incremental backups are stored in cloud storage and all full backups and archives are stored on LTO.
- Type Hybrid: All data of a given type, say employee data, is stored on LTO, while all customer data is stored in cloud storage. We see this hybrid use case occur as a function of convenience and occasionally compliance, although some regulatory requirements such as GDPR may not be accommodated by LTO solutions.
You can imagine there being other splits, but in essence, there may be situations where keeping the legacy system going in some capacity for some period of time is the prudent business option.
If you have a large tape library, it can be almost paralyzing to think about moving to the cloud, even if it is less expensive. Being open to the hybrid LTO/cloud model is a way to break the task down into manageable steps. For example, solutions like Starwind VTL and Archiware P5 allow you to start backing up to the cloud with minimal changes to your existing tape-based backup schemes.
Many companies that start down the hybrid road typically begin with moving their daily incremental files to the cloud. This immediately reduces the amount of “tape work” you have to do each day and it has the added benefit of making the files readily available should they need to be restored. Once a company is satisfied that their cloud based backups for their daily incremental files are under control, they can consider whether or not they need to move the rest of their data to the cloud.
Will Cloud Storage Replace LTO?
At some point, the LTO tapes you have will need to be migrated to something else as the equipment to read your old tapes will become outdated, then unsupported, and finally unavailable. Users with LTO 4 and, to some degree, LTO 5 are already feeling this pain. To migrate all of that data from your existing LTO system to LTO version “X,” cloud storage, or something else, will be a monumental task. It is probably a good idea to start planning for that now.
In summary, many people will find that they can now choose cloud storage over LTO as an affordable way to store their data going forward. But, having a hybrid environment of both LTO and cloud storage is not only possible, it is a practical way to reduce your overall backup cost while maximizing your existing LTO investment. The hybrid model creates an improved operational environment and provides a pathway forward should you decide to move exclusively to storing your data in the cloud at some point in the future.