Learning the basics of computer science lesson XVI

In our last class, we talked about the hard disk and then discussed all we need to know about it and how it functions in a system and the best ways we can take care of it given its relative importance in a system.

Therefore, we will start with the sub-topic:

How to care for the hard disk drive.

For all we know, when any damage is the root directory that renders the hard disk useless especially when the computer is on the hard disk and it is spinning fast of which any contact with it at all can cause pits or scratches.

Care here must be taken to keep the read/write head where I should be, which is just a more above the hard disk drive but would never by any default be touching it.

As we all know, turning off the computer and then quickly backing it up already before the spinning is noticed to have reached a stop, me that cause a very big damage.

* Disk formatting

Here, all magnetic disks are similarly formatted or divided into areas called tracks, sectors and cylinders.

The formatting process sets ups a method of assigning addresses to the different areas.

It also sets up an area for keeping the lists of addresses and without formatting, it would be like a Library where pages are not in books but are scattered around on the shelves, tables and floors as it will be very very difficult getting a book together.

Note: A formatting methods allows you to efficiently use the space while it is still being able to find the things that are stored in a disk.

* Clusters

This is the minimum space uses by any read/write head to read or write data.

It is a set of track sectors that ranges from 2-32 or more which is dependent on the formatting scheme in use.

The most common formatting a scheme for PCs sets the number of track sectors in a cluster bases on the capacity of the disk.

A 1.2 gig hard drive will have clusters twice as large as a 500MB hard drive.

So, there is often a lot of spaces in the cluster that is beyond the data that is stored there and while there are few schemes out there that reduces this problem, but it will never go away entirely and the only way to reduce the amount of slack space is to reduce the size of a cluster by changing the method of formatting and you could have more tracks on the disk, or else, more sectors on a track, or you could reduce the number of track sectors in a cluster.

The computer keeps track of what it has put where on a disk by remembering the addresses of all the sectors used, which would mean remembering some combinations of the cylinder, track and the sectors used.

Where the difference between addressing methods shows up is in the time it takes for the read/write head to get into the right position, the cylinder method writes data down the disks on the same cylinder and this works faster because each metal platter has a read/write head for each side and they will all move together.

Therefore, for one position of the read/write heads, the computer can put data on all the platters before having to move the heads to a new position.

Where the difference between the addressing methods shows up is in the time it takes for the read/write head to get into the right position, the cylinder method writes down the disks on the same cylinder.

This works faster because each metal platter has a read/write head for each side and they all move together.

Therefore, for one position of the read/write heads, the computer can put some data on all the platters before having to move the heads to a new position.

When a disk is formatted, the following takes place

• All data is erased

• Surfaces are checked for physical and magnetic defects and lastly,

• A root directory is created to list where things are on the disk.

Hope you remembered to stay safe still from covid19 pandemic? If you did, then all I have to say is good health to you👌.

Happy New year all🎉

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