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Perception


solbjerg

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Hi all

As far as I remember from school 50 + years ago we are able to percieve an image conciously at a speed of up to 20-25 frames per second, subconciously up to 50 frames per second if I remember correctly.

Therefore it is not allowed to make advertising that uses frames above what we notice conciously, otherwise they could plant in our minds that we had to buy a specific product without we being aware that this was going on. 50 frames per second is equivalent to 2 hundreds of a second per frame - which we don't even notice subconciously.

The speed at which a computer operates is much higher than this - it is usually measured in a few thousands of a second.

Therefore it is doubtfull that we will notice any change from a defrag for example, unless the disk is severly fragmented.

As far as I remember the speed of the discs in the harddisk is around 7000 revolutions per minute but I do not know how fast the reading heads goes to the inner tracks of the disc and back again.

Cheers

solbjerg

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As of 2008, a typical 7200 rpm desktop hard drive has a sustained "disk-to-buffer" data transfer rate of about 70 megabytes per second.

This rate depends on the track location, so it will be higher for data on the outer tracks (where there are more data sectors) and lower toward the inner tracks (where there are fewer data sectors); and is generally somewhat higher for 10,000 rpm drives. A current widely used standard for the "buffer-to-computer" interface is 3.0 Gbit/s SATA, which can send about 300 megabyte/s from the buffer to the computer, and thus is still comfortably ahead of today's disk-to-buffer transfer rates. Data transfer rate (read/write) can be measured by writing a large file to disk using special file generator tools, then reading back the file. Transfer rate can be influenced by file system fragmentation and the layout of the files.

 

From Wikipedia, the free encyclopedia

 

So you are pretty close and have good memory!

 

Did you know its considered a drive has a life span of around 600.000 hours but some have been recorded at, as long as 1.40 million hours.

Mr Bean

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Hi Mr. Bean

Thank you for the numbers

They yield a speed for the outer track of 22.5 m/s (strong gale) and for the inner track about 1 third of that let's say - 7,5 m/s (about as fast as we could run when we were young)

Available area for storage about 80 cm² per disc all of which together - today can hold maybe 1TB which means that every square cm can contain more than 1GB on each of the discs in the harddisk.

 

Where did you come across the lifespan of computers?

 

The first programmable general purpose computer in the world was the ENIAC (Electronic Numerical Integrator And Computer) demonstrated for the first time in 1948.

600.000 hours = 25.000 days = more than 68 years

1.400.000 hours = 58.333 days + 8 hours = more than 159 years

So the Eniac must have run 5-6 years before it was demonstrated and just recently died? - it used radio tubes and consumed as much power as a small town.

The other computer mentioned must have been given to us by some aliens in the eighteen-fifties :-)

If you divide the quoted hours by 10 it looks more plausible.

Cheers

solbjerg

 

As of 2008, a typical 7200 rpm desktop hard drive has a sustained "disk-to-buffer" data transfer rate of about 70 megabytes per second.

This rate depends on the track location, so it will be higher for data on the outer tracks (where there are more data sectors) and lower toward the inner tracks (where there are fewer data sectors); and is generally somewhat higher for 10,000 rpm drives. A current widely used standard for the "buffer-to-computer" interface is 3.0 Gbit/s SATA, which can send about 300 megabyte/s from the buffer to the computer, and thus is still comfortably ahead of today's disk-to-buffer transfer rates. Data transfer rate (read/write) can be measured by writing a large file to disk using special file generator tools, then reading back the file. Transfer rate can be influenced by file system fragmentation and the layout of the files.

 

From Wikipedia, the free encyclopedia

 

so you are pretty close and have good memory!

 

did you know its considered a drive has a life span of around 600.000 hours but some have been recorded at , as long as 1.40 million hours.

Mr Bean

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From Wikipedia, the free encyclopedia

{ basted ON laboratory environments}

 

The mean time between failures (MTBF) of SATA drives is usually about 600,000 hours (some drives such as Western Digital Raptor have rated 1.4 million hours MTBF),[66] while SCSI drives are rated for upwards of 1.5 million hours.[citation needed] However, independent research indicates that MTBF is not a reliable estimate of a drive's longevity.[67] MTBF is conducted in laboratory environments in test chambers and is an important metric to determine the quality of a disk drive before it enters high volume production. Once the drive product is in production, the more valid metric is annualized failure rate (AFR).[citation needed] AFR is the percentage of real-world drive failures after shipping.

I have read some users have hard disk still working perfectly after 10 years.

 

I have 20 to 500 meg drives still work perfectly, tho sitting in the shed, and have 20gig to 400 gig+ the same working no problems the latter in use.

 

Quote

Therefore it is doubtful that we will notice any change from a defrag for example, unless the disk is severely fragmented.

UN Quote

 

Yes you are also correct here.

 

Mr bean

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OK Mr. Bean

They must have some other method of measuring time.

Perhaps if they set up 100 harddisks and let then all run for 6000 hours → about 8 months and then encounter a harddisk failure they could claim that together all the harddisks had run 600.000 hours, but that does not tell us much about the average lifespan of a computer.

Cheers

solbjerg

 

From Wikipedia, the free encyclopedia

{ basted ON laboratory environments}

 

The mean time between failures (MTBF) of SATA drives is usually about 600,000 hours (some drives such as Western Digital Raptor have rated 1.4 million hours MTBF),[66] while SCSI drives are rated for upwards of 1.5 million hours.[citation needed] However, independent research indicates that MTBF is not a reliable estimate of a drive's longevity.[67] MTBF is conducted in laboratory environments in test chambers and is an important metric to determine the quality of a disk drive before it enters high volume production. Once the drive product is in production, the more valid metric is annualized failure rate (AFR).[citation needed] AFR is the percentage of real-world drive failures after shipping.

 

Mr bean

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The average life span of a desktop computer is about 4-6 years.MAX :

AS There are many variables that can reduce the life span tho, such as how much you use it and how hard you push it, environmental heat and humidity, dust, and insects.

 

I have seen instances of people with computers still working after ten to twelve years, I have 2 in that range. still satisfied with and keep running till they die. These are pretty rare though and only collectors keep them.

May I add you need to keep them running to stop the motherboard becoming brittle, and watch the inside for cleanness, they run 2 hours a day.

 

Most people need the new features that technology advances can provide, or additional hardware so they are replaced with the modern ones and the old ones traded in our recycled.

MR bean

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hi Mr. Bean

Two of my harddisks are 8 years old

The c:\ drive is getting a bit tired I think - the Power On Count 61 is below normal range by now - the rest of the readings are fine.

The D:\ drive is fine in all instances, but it is not used much other than storage.

So I am watching my C:\ drive and will probably soon buy a new harddisk.

The E: drive is older still, but have almost not been used - it is only 18 GB

Cheers

solbjerg

 

 

The average life span of a desktop computer is about 4-6 years.MAX :

AS There are many variables that can reduce the life span tho, such as how much you use it and how hard you push it, environmental heat and humidity, dust, and insects.

 

I have seen instances of people with computers still working after ten to twelve years, I have 2 in that range. still satisfied with and keep running till thy Die.These are pretty rare though And only collectors keep them.?

 

most people need the new features that technology advances can provide, or additional hardware so thy are replaced with the modern ones.

MR bean

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"Two of my hard disks are 8 years old"

Oh dear!

 

Well now you could be in a spot of bother, why I say that is and taking a punt at this. IE drives are no more .

Where you live I can't say, but as I understand it they stopped production of IE drives. Last year 2009.

 

Now we come to your PC, can it accept SATA drives? Is there an option to interchange (swap)(IE cables) to Sata cables.

You should be able to tell looking inside at the cables, thin yellow or red. Not the wide ones as used by IE drives.

Please check your PC manually, if it can, if not start looking now! for s IE drive.

 

My one you can NOT this one, bar a USB cable that will accept either type drive (readable)..

Mr Bean

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Hi Mr. Bean

You must be talking about IDE harddisks they are discontinued, but it is still very easy for me to buy fx. a 500 GB one (about 500 kr. here → 100$)

Even if I could not I would just change to a SATA, no problem.

I am from Denmark as you can see.

Cheers

solbjerg

 

 

 

"Two of my hard disks are 8 years old"

oh dear,

 

well now.you could be in a spot of bother,why I say that is.and taking a punt at this.IE drives are no more .

where you live I cant say, but as I understand it thy stopped production of IE drives.Last year.2009.

 

now we come to your PC , can it accept SATA drives? ,is there a option to interchange (swap(IE cables) to Sata cables.

you should be able to tell looking inside at the cables.thin yellow or red

Not the wide ones.as used by IE drives.

please check your PC manual, if it can, if not start looking now! for A IE drive.

 

my one you cant NOT this one ,bar a USB cable that will accept ether.type drive (readable)

Mr Bean

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Hi Mr. Bean

To round off the original subject

This is a reading head and three discs (platters) common size of today 300 GB → 100 GB per disc (platter)

http://forums.iobit.com/attachment.php?attachmentid=6447&stc=1&d=1291832226

As you can see the repose position of the reading head is at the inside rim about 1 cm from the center. The outside rim is about 6 cm from the center. When the computer is closed the reading head will be in its repose position. During operation it can be anywhere. i.e. sometimes far from the place it has to leave or pick up information or at other times very close by.

The discs rotates with the speed of normally 7200 revolutions per minute (120 revolutions per second) - I still haven't found the speed at which the reading head moves.

The capacity of the amount of information it can pick up in 1 second corresponds the the Mhz/Ghz at which the computer operates.

i.e. 2000 Mhz/2 Ghz → 2000 Mbits/per second (corresponds to ~250 Mbytes per second) (that is 250 million letters every second) - incredible! (maximum theoretical capacity)

The head moves above the platter with a clearence of 3µ (that is 3 thousands of a millimeter - 3/1000 mm) the way they have increased the amount of retrievable information is by lowering the distance the reading head is over the disc (platter).

I'll stop here :-)

Cheers

solbjerg

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