Databus Issue: 2008 2 07/17/2008
Progressive Incremental Backup Methodology
Garth Gomes Information Systems Manager
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This past year, the Los Banos USD IT department was in the process of updating our licensing and maintenance agreement for our existing backup software (traditional backup process). During the review process, we felt our existing software lacked an important enterprise function like incremental back ups, without the need for periodic full back ups. This was important to us since we backed up data from 75 servers, district wide, over the network. Occasionally, we had problems getting the periodic full back ups to successfully complete without interruption. This left our department vulnerable without reliable backups.
In order to correct this problem, we changed our direction and started looking at new software. The department’s goal was to save money, time, improve storage and conserve network bandwidth. While attending the vendor show at the CETPA conference last October, I met with Asif Jessani, IBM Client Representative for K-12 Education. We discussed Tivoli Storage Manager (TSM), which operates on a progressive incremental methodology that backs up only new or changed versions of files, thereby greatly reducing data redundancy, network bandwidth and storage pool consumption as compared to traditional methodologies based on periodic full back ups. We also reviewed products from Commvault and EMC. After meeting with IBM multiple times, we decided on TSM.
The reason we chose TSM was due to the way their back-up software handled incremental back ups. With the progressive incremental process, we did a complete or full backup of data during the initial process and incremental back ups thereafter (forever). The initial back-up process took one weekend to complete. The incremental process takes about 16 backup hours a day to complete, with no periodic full backups during the week.
Our old back-up software followed the traditional back-up methodology. Our weekly process was four incremental back ups during the week and a full back up over the weekend. This process took about 232 back-up hours weekly. After initial back up with TSM, our weekly back-up process only takes about 80 back-up hours to complete. Our back ups are more reliable due to the reduced time to complete the process.
Since the progressive incremental process only copies changed or new files, we are also saving about 2 TB of storage area and increased the amount of data stored over the traditional back-up process. With our old back-up software, we allocated a 5 TB storage pool which held about a month of back-up data. A 3 TB storage pool holds 12 months of data with TSM.
TSM also supports a range of storage devices such as a SAN, NAS or tape storage device. We only back up data to a Hitachi AMS 200 SAN. Our plan is to add a SAN tape device in the future. Tape continues to be a cost-effective alternative for off site storage. It is removable to protect against viruses and data corruption. It is portable, for off site storage, to be used for disaster recovery.
Other TSM features are data compression and encryption. Before backing up data over the network, it can be compressed. This will also conserve bandwidth. The 128-bit AES (Advanced Encryption Standard) will also secure the data prior to backing up over the network.
Tivoli Storage Manager, with the progressive incremental methodology, has reduced our back-up process cost, length of backup time, amount of data to backup, amount of storage area and network bandwidth consumption. We also saved $25,000 by purchasing TSM, rather than updating our licensing and maintenance contract for the old back-up software.
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Garth Gomes is the Information Systems Manger for Los Banos Unified School District. He can be reached at ggomes@losbanosusd.k12.ca.us.
