When we ask our customers what they spend on tape backup and storage, many don’t really know – or at least they don’t want to think about it. We thought it might be helpful to document the real costs of tape backup. Whether you are putting together a new backup plan, or considering how to cut the cost of your current plan, these numbers should help you better understand the real cost of tape backup.

Our Model Environment and System

Our example will be a typical SMB with 12TB of data to back up. We will break the process down and cost out each item in the process then combine all to derive the set up and annual costs. The standard drives that we will use will be LTO4/5 and the same with the tapes. We will also assume that a normal backup schedule would be one full back up each weekend, and a single daily incremental backup of a volume.

One Time Setup Costs

Hardware: We will assume only the tape library and the backup server for this exercise. We will assume the company has purchased a SAN switch environment for storage, or have opted for IP based storage in which case the server ports have been purchased as part of another budget. If desired, those cost factors can be added, but again, typically these are considered a facilities cost item rather than backup cost. Not all backup software environments support remote ndmp, so we will specify a SCSI or FC tape library rather than one of the lower cost SAS tape libraries.


Software: Typically, companies backup their most critical software modules and data. Mail, database, and financial data are all critical to the company, and are basically a database in their structure. We could include business critical software requiring add on modules such as SAP, Informix, or particular storage vendor snapshot products. However, for this study, we will assume SQL databases being written to flat files in a storage location that gets backed up and Email. Many financial packages rely on databases on the backend, so we will add in two additional cost modules to a backup software standard offering and also a VMWARE module for the virtualization environment.

Cartridges Required and Acquisition Cost

Tape Capacity: A real world expectation for actual data held on a tape is about 70% of the rated capacity of a tape. The biggest issue in writing to tape is the header written for each file, with databases, exchange, and most configuration management storage actually closer to the lower end of the tape storage capacity per media unit.
Example:
LTO4 – 800GB/1.6TB rated, but in reality you are lucky to get 1.1 TB of data written to a tape.
LTO5 – 1.5TB/3TB rated, but would fill at about 2.1 TB (database and smaller files would get much less on a tape)

Our site with 12TB requires 6 LTO5 cartridges (2.1TB) per full backup. The amount of incremental backups in one month is the equivalent of one full backup. So if a month has 4 full backups, the formula to use becomes: 4weeks full + 1 full (incrementals accumulated) = 5 weeks total.

For a year, you calculate 52 weeks full + 52/4 = 52 + 13 = the equivalent of 65 weeks of full backups. Our site that requires 6 tapes for a weekly full backup per the formula yields: 4x6 + 1x6 = 30 tapes a month 52x6 + 13x6 = 390 per year Tapes require custom labeling with meaningful ID for each tape to a company schema. Pre-labeled tapes cost about $65.00 per tape. Unfortunately, tapes come in boxes of 20, and even if you accurately project the number of tapes you would purchase for the year at 390 tapes you have to purchase 400 tapes – $65.00 x 400 = $26,000.00

Consider that the company also wants to keep a rotating quarterly archive for a year, and then one annual archive. This now means you have to increase your offsite storage by four weeks worth of tapes to cover the quarterly archive, and replace 6 tapes a year. The total tapes out of rotation for archiving with a retention policy of 6 months would mean an additional 12 tapes. Finally, add 5 tapes to the mix to account for bad tapes and tapes destroyed in use and we need to add 17 tapes to the previously determined 390 tapes making the total 407 tapes.

From our earlier discussion on packaging, we have to round up to 420 = $65.00 x 420 = $27,300.00

Operating Expenses (Annual)

Offsite Storage Costs: The cost of storing a tape offsite per month is 1.10 per tape. Tape retention cycle is 6 months. The offsite storage for the year is12months x 390tapes x $1.10 = $5148.00.We will also have to adjust for the additional 12 tapes (rotating quarterly archive) to be located offsite at $1.10 each. 12 tapes x $ 1.10 each month x 12 months = $ 158.40 extra for the archive. Our revised total is $5148.00 + 158.40 = $5306.40

There are no charges for the weekly scheduled pickup and drop-off, but there is a $120 charge for any special request (usually, a critical restore that cannot wait for the tapes to be returned from the offsite storage facility). We’ll estimate there is one every two months that has to be performed. Therefore, the total amount becomes 6 specials per year x $120 = $720.00 special drop-off/pickup charges, so $5306.40 + $720.00 = $6026.40 annually for offsite tape costs.

Also, if we have to retain an annual archive for 5 years, the 6 tapes per year would add an additional cost at the following rate: This means depending upon what year we are into the 5 year retention period, we should add up to $396.00 to the tape and quarterly archive cost to date.

Labor Costs: You have to have a person receive the tapes, mount the tapes, and remove the tapes from the unit, in addition to the staff to perform the restore operation and notify the customer. We estimate this activity would take 8 man-hours a week, which also includes scanning, boxing, ordering, and possibly labeling the tape. 52 x 8 x $20.00 ($12.00 salary + $8.00 benefits costs per hour) = $8320.00 annually

Summary of First Year Costs:

Ongoing Annual Run Costs:

Now What?

As we’ve shown above, the cost of backing up just 12TB is considerable, with an investment of $100,000 by year two. Many businesses are moving to disk archives, mirrored systems at remote locations, or other forms of disk to disk backup. These options offer faster transfer rates which minimize backup windows, allow quicker, more reliable restores, and depending upon their structure, provide redundant platforms in the event of major failure.

If you would like to explore alternatives to tape backup, please contact Zerowait for an assessment of your current architecture and suggestions on how to implement an effective disk to disk backup/mirror architecture.