1. Answer all parts of the questions and Consider the following backup Schema: .
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Question
1. Answer all parts of the questions and Consider the following backup Schema:
. Day 1. Copy to a back up medium all files from the disk.
.Day 2. Copy to another medium all files changed since day 1.
.Day 3. Copy to another medium all files changed since day 1.
This differs from the schedule given in Section 11.7.4 by having all subsequent backups copy all files modified since the first full backup. What are the benefits of this system over the one in Section 11.7.4? What are the draw backs? Are restore operations made easier or more difficult? Explain your answer.
System in Section 11.7.4:
.Day 1. Copy to a backup medium all files from the disk. This is called full backup
.Day2. Copy to another medium all files changed since day 1. This is an incremental backup
.Day3. Copy to another medium all files changed since day 2.
.
.
.Day N. Copy to another medium all files changed since day N-1. Then go back to Day 1.
Explanation / Answer
Several different kinds of backup methods can be used, often in concert with each other:
Full: Backup all files on the system. (This is what you are doing on day 1, in both the methods.)
Incremental: Backup all files that have changed since the last incremental or full backup. ( This is what you are talking in Section 11.7.4)
Differential: Backup all files that have changed since the last full backup. (This is what you are talking in your recent method.)
Multiple level incremental: Backup all files that have changed since the previous backup at the same or a previous level.
User: Backup only files in a specific user's directory.
Advantages and disadvantages of the technique you tried:
DisAdv: As you move for the subsequent days, the amount of data that is backed up by the differential backup will increase because the changes accumulates, whereas, in incremental backups, the increase may not be to that extent, as you backup only the data that differs from that of the previous incremental backup.
DisAdv: If your data is very volatile, your differential backup might back as much data as the full backup. Here, it is really time consuming, when compared to that of incremental backup.
Adv: The important advantage of this technique is, you only need 2 disks, the most recent differential backup disc, and the full backup disc, to restore fully. Whereas, in incremental backups, you need all the intermediate discs, from the most recent incremental backup, to the most recent full backup. Its like stepping back, each and every step carefully.
Restore operations are made easier or difficult with this technique: Definitely we can say that restore operations, are made easier, as you need only 2 discs, to restore, and there are no intermediate stages, to restore, as opposed to that of incremental backups. In incremental backups, you have to step back every step, whereas, here, it is like you are moving back to a safe position of the begining.
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