Tape Drives: The Complete Range

The first thing that comes to mind when you talk about data backup is a tape drive. That's because the tape still reigns supreme when it comes to low cost, high volume data backups. It still remains the most preferred medium for data backup over other media such as CDs, DVDs, zip drives, etc. 

We reviewed seven different tape drives in this shootout, with a lot of variety in both technology as well as usage. It is perhaps the first time that we have received so much variety in a tape-drive shootout. 

Among the seven models, atleast six of them used either different technologies or different generations of the same technology. The cost of drives that we received varied from Rs 27,500 to more than Rs 2.5 Lakhs, and likewise, the native backup capacities also ranged from 20 GB to 400 GB. 

Not only that, we even received models with both SCSI and IDE interfaces, external as well as internal drives (although the IDE model didn't work finally). We have also carried a glossary to explain various technologies used in tape.

What to backup?



When going for a back-up solution, the biggest question which we face is to decide what is the amount of data one wants to back up. Do we need to backup all the data available on our server or just a selection of it? As a scenario, let's assume that you have network of 50 users/nodes and each node has a 40 GB hard drive and additionally you have a server with a 100 GB of data on it. Now if you want to back up all of this data, you need capacity for 4,100 GB of data (40x100 +100 GB). Now if some 50% of this is just MP3 files and movies that users have stored in their machines, then you would be wasting a lot of money to back it up. So you should identify how important the data you have is and according to that select a solution that suits both your requirement as well as your pocket. 

No winners this time!



This time, we have not declared any winners, because we could not place the drives we received into a single category. 



Instead, we decided to focus on the range of drives we received. 

As usual we used our three-axes model of performance, features and price analyze them. 

The test bed



We tested all drives on an IBM eServer 225 with Dual Xeon CPUs, 2 GB RAM and an Ultra-320 SCSI HDD. We used the Ultra 320 disk because it has a much higher speed than any of the tape drives we received. This made sure that any loss of speed was at the tape-drive's end only. There were two types of tests that we performed on all drives. In one test, we backed up 16 GB of data in both compressed and uncompressed modes, and then restored this to the hard disk. Therefore, this one test covered four different tests. The data set was a mix of image files (BMP, TIF, JPG), Word documents, MP3s, movie files and even some EXE files. We used the same data set across all drives. In the second test, we took a single large 800 MB compressed file and backed it up to the tape. This was to check how well a drive handled a continuous stream of data. With such data, the drive does not have to wait for data and has to spin continuously. For all these tests, we used CA's Brightstore ARCServer Backup software. We measured two things during each backup and restore operation-the speed of backup/restore, and the transfer rate. This was done for both compressed and uncompressed modes. 

Pricing: We considered not only the cost of the drive, but also the cost per GB for the cartridge because the latter is a recurring investment, which can be significant. 

Besides this, the warranty is also important. 

Features: There aren't too many features in a tape drive, because at the end of the day what matters is that it should be capable of backing up as well as restoring data reliably.

Therefore, we only looked at four parameters under features. These were backward compatibility, rated cartridge life for end-to-end usage and shelf life, software bundle, cleaning cartridge and special features such as LCD screen/diagnostic LEDs. Here, backward compatibility is extremely important because technology changes in this segment are fairly common. You buy a tape drive today, and its technology changes a few years down the line, and the new

technology should be able to read the data from the older one. So, check whether the drive you buy has a future roadmap, and the future drives would be backward compatible with the existing technologies.

Anindya Roy and Sanjay Majumder