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Home > Support > Knowledgebase | Saturday, November 22, 2008 |  |
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Why does my account seem to show that I have less space than I purchased?All media manufacturers measure the size of their media, hard drives and all other storage media including tape, CDs, DVDs using a decimal numbering system. All storage media are designed and marketed by their manufactures in this way using the familiar decimal measurement of their capacity. (Using powers of 10) Some writers say this format began when the old paper punch cards were the normal method for inputting and storing data. Many Operating Systems, including the Microsoft family, measure storage capacity in a binary based measuring system. (Using powers of 2) This will result in an apparent loss of size when the capacity is viewed in Windows. In PC Data Backups software you will see this binary measurement presented in the Windows format when viewing the Backup View tab. The 4 GB plan will be displayed as having a backup limit of: 3.97 GB. The 10 GB plan will show up as having a backup limit of: 9.77 GB. The 30 B plan will show up as having a backup limit of 29.3 GB. This is normal. If you purchase a hard disk drive; when you install in on your computer, you will observe a similar conversion takes place, when you look at the drive properties it will display as smaller than the size of the drive you purchased. A further explanation is detailed below: Writing for wikpedia.org, JJLatWiki, in an article titled Why decimal bytes for HDD? dated 18 July 2005 16:09 (UTC), stated: "Hard disk drive manufacturers state capacity in decimal units. Since most computer operating systems report drive usage and capacity in binary units, the difference causes an apparent loss between the advertised capacity and the formatted, usable capacity." "This usage has a long engineering tradition, and was probably not influenced by marketing. It arose because nothing about the physical structure of the disk drives makes power-of-two capacities natural: the number of platters, tracks and sectors per track are all continuously variable." "The decimal unit capacity in hard disk drives follows the method used for serially accessed storage media which predated direct access storage media like hard disk drives. Paper punch cards could only be used in a serial fashion, like the magnetic tapes that followed. When a stream of data is stored, it's more logical to indicate how many thousands, millions, or billions of bytes have been stored versus how many 1024, 1,048,576, or 1,073,741,824 bytes have been. When the first hard disk drives were being developed, the decimal measurement was only natural since the hard disk drive served essentially the same function as punch cards and tapes. Thus today, any device that is addressed or seen as "storage" uses the decimal system to identify capacity." JJLatWiki 18 July 2005 16:09 (UTC) |
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