3. File Systems: Lesson Nine

Question 1

How are disks, partitions, and volumes different from one another?

Answer 1

Disks are the storage hardware.
Partitions are logical disk divisions that are used to define storage space.
Volumes, contained inside partitions, are used to define how individual files and folders are saved to storage.

Question 2

What are the two primary partition schemes for Mac-formatted disks? What are their differences?

Answer 2

GUID Partition Table is the default partition scheme on Intel-based Mac computers.
Apple Partition Map is the default partition scheme on PowerPC-based Mac computers.

Question 3

What two volume formats are supported for an OS X system volume?

Answer 3

The volume formats supported as system volumes for OS X are:
• Mac OS Extended (Journaled)
• Mac OS Extended (Journaled, Encrypted)

Question 4

How does file system journaling work?

Answer 4

File system journaling records which file operations are in progress at any given moment.
This way, if a power failure or system crash occurs, after the system restarts, it will be able to quickly verify the integrity of the volume by “replaying” the journal.

Question 5

What is Core Storage, and what two major OS X features are implemented via Core Storage?

Answer 5

Core Storage is a file system management layer that’s used by OS X to provide disk encryption as used by FileVault, and combine separate disks as used by Fusion Drive.

Question 6

What are the four erase options available in Disk Utility? How are they all different?

Answer 6

The four erase options in Disk Utility are:

1. Replace the volume directory structure. This is the fastest way to erase data.
2. Write zeroes on top of the previous disk data. This is a secure way to erase data.
3. Write three separate information passes on top of the previous disk data. This provides a more secure way to erase data.
4. Write seven separate information passes on top of the previous disk data. This is the most secure way to erase data.

Question 7

How does the Secure Empty Trash feature in the Finder work?

Answer 7

Secure Empty Trash performs a 7-pass erase on Trash contents.

Question 8

How can you ensure that previously deleted items are securely erased?

Answer 8

From the Erase tab in Disk Utility, you can choose to securely erase the free space of a disk or volume. This securely erases any previously deleted files on the selected disk or volume.

For SSD, see: https://support.apple.com/en-us/HT201949

Question 9

How can you encrypt a disk without losing its contents?

Answer 9

From the Finder, you can encrypt a disk without losing its contents by secondary (or Control-) clicking the disk and choosing Encrypt from the shortcut menu.

Question 10

What are the four ways can you eject a volume or disk from the Finder?

Answer 10

The four ways to eject a volume or disk from the Finder are:

1. Drag the disk icon to the Trash.
2. Press and hold the Eject key for a few moments to unmount and eject optical media.
3. Select the volume you want to eject and choose Eject from the File menu.
4. In the Finder sidebar, click the small Eject button next to the volume you want to unmount and eject.

Question 11

What’s the potential side effect of improperly unmounting or ejecting a disk or volume?

Answer 11

Improperly unmounting or ejecting a drive or volume may cause data corruption.
The system automatically verifies and repairs an improperly unmounted or ejected volume the next time it becomes available to the Mac.