Question

At Petco Animals 2 pages summary.

1. What were the data backup problems when Petco used tapes?

2. What were the data backup problems when Petco used mirroring?

3. What are the disadvantages of using DAS, and how are these disadvantages compounded when a company grows?

4. What benefits did Petco acquire when adopting the current technology for backing up warehouse data?

Answer 1

1- here the latency of few hours posed a problem. If electricity was lost so was the many hour data. Also it was labour intensive. Rewinding tapes was time consuming.

2- in mirroring if the original disk is corrupt such as infected with virus so will be the mirror disk.

3- Many disks were underutilized and also the sharing of stored data was a challange.

4- System could be installed without intereferences from warehouse operations. It reduces the total amount of required disk capacity.

Answer 2

1. Tape backup was reliable, but the latency of a few hours posed a risk. If electric power was lost, so was several hours of data that could not be recorded. Also, recording on tape is labor-intensive, because tapes must be manually mounted and dismounted. Rewinding tapes is time-consuming, and therefore delays availability of new tapes for recording.

2. In disk mirroring, the entire disk is automatically copied to a backup disk. While this reduces labor and makes data available immediately from the mirror disk, it also presents a problem. If the original disk is corrupt, such as infected with a virus, so is the mirror disk.

3. DAS (direct-attached storage) approach: each computer backed up to its own magnetic disk. The data could not be shared by all computers. This created two problems. Many of the disks were underutilized; much space