USB Flash Drives

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Partitioning and Formatting[edit]

Partitioning[edit]

Partitioning creates one or more areas on a disk that can be accessed by an Operating System. There are two partitioning schemes in common use, Master Boot Record(MBR) and GUID Partition Table. GUID is usually the better choice for disks over 2TB. The scanner console PC is unable to mount a drive formatted with GUID. If you are going to use a drive with the scanner console always partition it with Master Boot Record. We don't know why. Windows 7 is supposed to work with GUID.

Flash drives come factory partitioned with MBR. If your drive behaves strangely with the scanner PC check the partitioning scheme. Changing the partition scheme will erase the entire disk.

Formatting[edit]

Formatting sets up an empty file system on a partition. The are many disk formats including FAT32, exFAT, NTFS, ext4 and MacOSExtended(Journaled)(HFS+). ExFAT is the best choice for interchange between Windows and MacOS.
ExFAT is slow on MacOS. We found that large DICOM writes to an exFAT formatted drive take twice as long as one formatted HFS+. Journaling in HFS+ improves reliability. We recommend MacOSExtended(Journaled) formatting for transfers between MacOS computers.
Ubuntu can read and write exFAT formatted partitions. Ubuntu can read HFS+ formatted drives. HFS+ write works only with journaling disabled which we do not recommend.

Recommended USB Flash Drives[edit]

We recommend the following. All have been tested and found to offer satisfactory performance with imaging data. Prices checked 29 August 2018.

  • San Disk Extreme Go 64GB £21.59
  • Kingston HyperX HXS3 64GB £38.98
  • San Disk Extreme Pro 128GB Solid State Flash Drive £72.99. Was £54.59 on 9 August

The San Disk Extreme Pro is significantly faster than the two. Large image data transfers complete in about half the time. Prices change all the time. Presently the San Disk Extreme Go is the best value for money.