Friday, February 10, 2012

4K sector size

I am sure we have all read about hard drives with sector sizes greater than 512 bytes (0x200).  This week I saw my first one. A 1TB Iomega drive, with USB 3.0 connection.  The customer had lost their data, and sure enough when plugged into a Mac, there was nothing.

Looking at the disk, the first surprise was the sector size was 4096  (0x1000) bytes.  On first loading, my software did not like it but fortunately the fix was very quick to implement.  The software was expecting the boot sector signature of 0x55 0xAA to be at the end of the sector, rather than the end of the first 0x200 area.  By fixing this small problen, CnW recovery read the disk without problems.  Logically, the Mac disk is still based on 0x200 byte sectors so the program has a simple read function that translates a logical sector number into a disk logical block address (LBA) and the extracts the sector.

Be warned, more of these disks will be on their way.

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