How to set up an external hard drive for use with OS X

When you first attach a new external
hard drive to your Mac, it should mount
and be ready to use; however, before
relying on it, consider first taking a
couple of precautionary steps to ensure
that the drive continues to work as
expected.
One of the first things to take into
account is that the drive is likely
preformatted to FAT32 instead of a more
OS-specific format. Since FAT32 is
readable and writable on both Windows
and OS X systems, this is quickest way for
a drive to work on each platform;
however, it does have some limitations,
including the lack of journaling support
that would help prevent data corruption,
and lack of support for filesystem
permissions. In addition, FAT32 drives
usually come with the Master Boot
Record partition scheme, which does not
work with Apple's CoreStorage routines,
and therefore will not allow OS-
supported encryption of the drive
(among other customizations).
Sometimes drives will come with special
drive management software on them
that will give you options for partitioning
the drive and backing up your files to it.
While these may be convenient, they are
not the most recommended approach to
managing the drive. For one, unless the
drive uses a special multidisk RAID setup,
OS X already comes with all the necessary
tools for managing the drive. Additional
tools from third-party manufacturers
may lead to compatibility problems, as
was recently seen when incompatible
drive management software resulted in
data loss for a number of people who
had upgraded to OS X Mavericks.
Because of this, if the drive you have
purchased is a special RAID array, then
you may have to use the manufacturer's
setup; however, if it is a single-drive
device, then before using it be sure to
format it using Disk Utility in OS X. If the
drive is going to be used only with your
Mac and with other Macs, then consider
using Apple's Mac OS X Extended
(Journaled) format, and only use FAT32 if
you intend to use the drive with a
Windows system.
To format the drive, attach it to your
system and open Disk Utility, and then
perform the following steps:
1. Select the drive device in the list of
devices, which is the item above any
storage volumes on the drive, and
which may show the manufacturer
name, media size, and so on.
2. Choose the "Partition" tab that
appears.
3. Select "1 Partition" from the drop-
down menu (or more, if you have
specific need for more than one
volume).
When you select a new partition
layout from the drop-down menu,
each new partition will be formatted
to Mac OS Extended (Journaled) by
default, but be sure to double-check
this by selecting each in the partition
diagram and then choosing the
format for it.
4. Click the Options button and ensure
"GUID" is selected as the partition
scheme.
5. Click Apply to save the changes.
When this is done, the disk should
unmount and then remount with the
new formatting settings, and now be
ready for use. Generally a format of the
drive in this manner is all that is needed;
however, some people may wish to test
drives further to make sure the media
does not contain any bad blocks or other
errors beyond the scope of the drive's
formatting.
For most in-depth testing of drives, a
third-party tool like Drive Genius or Tech
Tool Pro can be used, but Disk Utility
does support one option, which is to use
the Secure Erase option to write zeros to
the disk surface. To do this, select the
volume, then click Secure Erase in the
Erase tab, and drag the Secure Erase
slider to the second position before
clicking OK. This will cause each available
data block to be accessed and written to,
and if one is bad then the disk will
allocate a spare block in its place and
ensure that the logically writable storage
space is available for use. Secure Erase
and other similar options that test each
storage block of a device may take a
number of hours to complete, but it
reduces the number of potential
problems with the drive.

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