Snow Leopard misreads disk size

  • Posted: 19 September 2009 05:04 AM

    I have a 20’ iMac with 250GB hard drive that I have just upgraded to Snow Leopard with an annoying side affect….

    Before the SL installation I had 73.9GB free on the hard disk. I don’t think it’s relevant but at the same time as installing SL I upgraded the RAM to 3GB.

    After the installation the capacity of the hard disk in Finder has ‘grown’ to 319.73GB and I now have 92.35 GB free on the disc however I have used 227.38GB which doesn’t add up!!  I also have a 250GB external hard drive attached as a time machine backup and that is also shown as being 319.73GB in size but with 10.64GB free.

    Has anyone else had the same issue and what’s the solution to get an accurate reading?????

    Many thanks



    Recent switcher

  • Posted: 21 September 2009 02:14 PM #1

    Apple has a knowledgebase article on this. Hopefully in answers your question:

  • Posted: 07 October 2009 06:41 PM #2

    The default size in Snow Leopard is now base 10, instead of base 2 numbering.  This means that a drive sold as a 250gb drive will actually show a size of 250gb in Snow Leopard instead of the ‘real’ size.

  • Avatar

    Posted: 07 October 2009 07:54 PM #3

    Folks, read the OP carefully.

    He has a 250GB drive now reading effectively 320GB.  SL will read a 250GB drive as being 250GB, whereas previously it would read around 220GB. He should not be seeing 320GB unless something is wrong or the drive is actually 320GB (which they sometimes do…sell a larger capacity drive and only format to a lower capacity because they ran out of the lower capacity platters).

  • Posted: 09 October 2009 12:52 PM #4

    Open Hard Disk Utility from the Appleications/Utility folder and fidn your HD. Let us know what the disk descripton says and the total capacity is listed as.

    I suspect the last poster is right, you just got a larger HD due to 250GB HD shortages. You either didn’t notice before or Snow Leopard somehow expanded your partition sixe.

    The before and after free space sizes you reported is somewhat typical for Snow Leopard installs, so I’m suspecting it’s jsut a case of you always having a 320GB HD all along and not noticing.