Sample Question:

From Sample Paper 1 - 2014:

JSR Notes:

There are two different ways of looking at data loss; one is where you can actually lose or damage the one and only form that data is stored, like if you lose your laptop, and you have no backup of its data. But this assessment statement is geared more toward preventing permanent loss of data via backup.

Preventing Physical Data Loss

i.e. Preventing accidents, damage, and theft:

• Keep away from liquids (both humid environments, and water/drinks, like milk) .
• Keep magnetic media like conventional hard drives away from magnets.
• Keep a back-up power supply (Uninterrupted Power Supply = UPS), so transmissions don't get corrupted.
• Keep enough space on hard drive to help prevent crashes that can happen if hard drives get too full.
• Take care of the computers/machines in general, including restarting regularly, and "doctoring" the computer
• Keeping physical data secure from theft and vandalism by locking doors to rooms with IT, plus use of CCTV other conventional security techniques.

Preventing Permanent Data Loss Through Redundancy

i.e. having more than one copy of data:

"Redundancy" - Redundancy is the general term for having more than one copy of data, in case the original copy gets corrupted, damaged, lost, or stolen.

Removable Media

By removable media we mean storage media that can have a backup of the data of a device stored on them. So, for example, a removable flash stick (though this is not the most reliable of storage media), or hard drive, or even CDs/DVDs, along with tape drives, which actually can have enormous storage capacity. That removable media device can then be used as backup if the main device has a problem. It is often best to take the removable media backup "off-site", meaning some place different, so that if there is a fire or flood etc. both the original and backup will not be lost.

Failover Systems

A failover system is a system which can completely take over from the original system. Usually we don't think in terms of just storage, but also of processing. So if a particular server goes down, there is a failover system that can immediately take over it's operation, and use a completely mirrored backup of the data it uses.

For example, say there was a breakdown of part of a system you were using to do an online purchase. If that breakdown occurred in the middle of the transaction, you wouldn't even know it, and the transaction would continue as normal, taken over by the failover system.

One particular way to achieve "failover" with regards to data is using a *RAID structure for hard drives. See the full description below, but it allows for any one particular hard drive to fail, without loss of data, since each hard drive is mirrored.

Off-site/On-line Storage

Off-site storage, as mentioned above, is storing a backup copy of your data some place other than where the original is kept. Thereby, if the original copy of the data is affected by some physical misfortune limited to a certain physical space, such as theft, or fire, the backup will not be affected.

On-line storage is storage to "The Cloud", in which, via the Internet, your data is carried regularly to a server farm that maintains another copy of your data. If this is done in a backup way, redundancy is achieved by the "off-site" nature of saving to the cloud. And if the original storage itself is done completely via The Cloud, then it is assumed that the cloud service has its own top notch redundancy systems.

*RAID

One popular and effective back-up strategy is to have hard drives set up in a RAID, which stands for a Redundant Array of Independent Disks, a system that mirrors and/or stripes some or all of the data.

• Mirror and Striping Backup Redundancy example with four hard drives arranged in a "RAID 10".
  • Hard drive #1 and #2 will be mirrored (so 2 is an exact copy of 1), plus #3 and #4 are also mirrored (4 is an exact copy of 3).
  • Further, data is written or read to/from 1 and 3 at once or 2 and 4 at once, which makes reading and writing twice as fast. This is called striping data - where files are written across more than one disk.

So we can say that a RAID 10 stripes data across mirrored pairs.

And as a final important point, do note that the prime focus in the assessment statement is on backup.

 

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