Apple Apfs Media Erase

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internalwill move the journal for device back locally.

For some locations of devices (e.g. internal hard disks), consideration of ownership settings on FSOs is the default.
For others (e.g. plug-in USB disks), it is not.

When ownership is enabled, the Owner and Group ID settings that exist on the disk are taken into account for determiningaccess, and exact settings are written to the disk as FSOs are created.
When ownership is disabled, Owner and Group ID settings on FSOs appear to the user and programs as the current user andgroup instead of their actual on-disk settings.

Enable ownership where a disk contains FSOs whose User and Group, and permissions, is critically important, such as when the plug-in disk contains system files to be changed or added .

File Systems formats
These (case insensative) personalities can be used for erasing and partitioning.

Did you back up the partition table? See gdisk

• APM Apple Partition Map , for a start up disk on PowerPC-based, a non-startup disk with any Mac, or a multiplatform compatible startup disk.
• MBR Master Boot Record . DOS/Windows-compatible
• GPTGUID Partitioning Table. for start up disk on Intel-based Mac.

• FSFormatare shown at listFilesystems and are created with the appropriate newfs_* (example newfs_hfs).
  The partition type is set according to the filesystem.
• vName: volume names must conform to file system specific restrictions.
  %noformat%: the partition is left uninitalized.
  Names are ignored but dummy names must be present.
• pSizeare floating point numbers followed by a letter or percent sign
  (example: 16G, 55.3T, 678M, 75%, R). Rwill use the Remainder of space on disk

  The last partition will be lengthened to the end of the disk.
  To create a partition of a specific size, include an additional partition with size of R

File System blocksize will be 4,096.
To change block size after creating a partition use: newfs
newfs_hfs -v VolumeName -b 8192 /dev/disk0s2

This will cause the average unused space per file to be 4,096 (i.e. 1/2 block).

When determing size:
( 3/18/16 DATA vol has 189,624 files
df reports 21,014,072 1k blocks used of 44,384,728 This is a space accounting only.However ( 21,014,072 1k blocks / 189,624 files total = 110 blk/file average aka ) means 2048*nfiles = unused space, (4096-2048)*nfiles will require ADDITIONAL unused space)

A size of limits displays the range of valid values for the current filesystem.
A size of mapsize displays:
A size of R will ATTEMPT to resize the partition to the maximun available. (DGG: didn't work )

Valid pnSizeare in the format of n.f units
Valid unitsare B(ytes), K(ilobytes), M(egabytes), G(igabytes), T(erabytes)
Example: 10G(10 gigabytes), 4.23T(4.23 terabytes), 5M(5 megabytes)

When decreasing size, optionally supply a list of new partitions to create.

Example:

When decreasing the size, new partitions may optionally be created to fill the newly-freed space.
To do this, specify the numberOfPartitions, format, name, and size as with partitionDisk

Resizing a volume that is currently set as the computer's startup disk will invalidate that setting; use the Startup DiskSystem Preferences panel or bless to reset the resized volume as the startup disk.

1. Single-pass zero-fill erase.
2. Single-pass random-fill erase.
3. US DoD 7-pass secure erase.
4. Gutmann algorithm 35-pass secure erase.
5. US DoE algorithm 3-pass secure erase.

While attached, the 'handle' by which a Container is identified is its Reference disk (device).

Reference disk is a synthesized whole-disk which is exported by APFS for identification purposes only; it has no storage. Apple shortcuts on mac. It is associated with the AppleAPFSContainerScheme node in the IO Registry.
An APFS Volume device identifiers appear to be of a related form, do not use the Container Reference as a basis to create device identifiers ; use the listingverbs with plist options

An APFS Physical Store disk is not necessarily a disk from a partition map; it could be e.g. anAppleRAID Set disk. Do not assume that an APFS Physical Store's disk identifier is a 2-part form such as disk0s2.

reserve size requests an assured minimum capacity for an APFS Volume.
If successfully created, the Volume is guaranteed to be able to store at least this many bytes of user file data.beyond this, the Volume might be able to store even more until constrained by reachingzero free space in its parent Container or by reaching a quota, if any.
Use a reserve to prevent running out of capacity due to competition from other Volumes or from a Container shrink attempt.

Quota size applies a maximum capacity to a Volume, limiting the numberof bytes of user file data which can be stored on the Volume.
It may not be able to reach this limit if its parent Container becomes full first.
Quota enforces accounting or to manage against 'unfair' premature filling-up of the parent Container due solely to thisVolume at the expense of sibling Volumes.

Efficient file copy cloning (copy-on-write) is supported (see copyfile (3)'s COPYFILE_CLONE).

File-level encryption is supported.

Snapshot represents a read-only copy of its parent APFS Volume, frozen at the moment of its creation.

Snapshots are neither listed nor discoverable when their Volume is not mounted.
Snapshots are uniquely identified within their parent Volume's namespace by either a numeric identifier (preferred) or by their name; Snapshots can be renamed.

Snapshots are mountable; provide a read-only historic version of the Volume

You can revert the present state of an APFS Volume back to equality with a Snapshot in its history.
This is a destructive reset/restore operation: Once a Volume is reverted, it cannot be brought forward.
Any Snaphots between the revert point and the present are lost as well.

Deleting a Snapshot; removes the possibility of ever reverting to that Snapshot's state,

Snapshot mount point's 'source device' is the Snapshot name followed by '@' and the 'parent' Volume's device node,
e.g. SnapName123@/dev/disk2s1 '. See mount_apfs -s (8) and fs_snapshot_create (2).

All currently-attached APFS Containers in the system are listed unless you specify acontainerReferenceDevice, which limits the output to that specific APFS Container family.

If -plist is specified, then a property list will be emitted

Volumes are unmounted first. If one or more is busy the operation is aborted.

Container's former Physical Store disks will be reformatted as HFS.

New name, default :Untitled .

If there were multiple Physical Stores, a space and a number suffix is added for each.

If Container is damaged, a Container Reference for it might not exist or it might not befunctional. reclaim former APFS Physical Store disk(s) by specifying -force ;
this activates an alternate last-resort mode.
In this mode, if you had more than onePhysical Store (e.g. the Fusion case) and the Container is sufficiently damaged, you might have todelete each Physical Store manually. avoid

size of limits outputs a range of valid values.

size of 0 to grow the targeted Physical Store such that all remaining space is filled to the next partition or the end of the partition map.

Shrinks are constrained by the amount of data usage by all APFS Volumes on the targeted or impliedContainer. Contributing to this includes quotas, reserves, the usage of Snapshots (e.g. by Time Machine), and metadata overhead.

When shrinking, new partitions may be created to fill the newly-freed spaceby specifing the format, name, and size parameters as for partitionDisk

Grows are constrained by the amount of partition map free space trailing the targeted or implied Physical Store partition.

All Volumes on the Container must be unlocked.

The new Volume will be unencrypted unless one of the passphrase options is specified
the user which is added will be the 'Disk User'.
passphraseHint can be displayed while Volume is locked.

volume's file usage to a maximum amount; no more than that many bytes will be available for filedata, even if there is otherwise enough space in the parent Container.
the reserve is not larger than quota.

Volumes carry certain metadata hint flags;
supply the role parameter with any combination of one or more of B R V or 0 as a no-op for scripting convenience.The new Volume is mounted after creation; unless -nomount is specified.
If mountpoint is specified it must exist

The 'new' Volume will inherit the file system type (Case-sensitiveness ) but not attributes such as name, reserve, quota, or encryption status.

If you need more control, delete;add the Volume.

-user disk then the Disk UUID (which equals the Volume UUID) user is assumed;
-user UUID that specific user is assumed;

-recoverykeychain then the Institutional Recovery user (see below) is assumed.
-recoverykeychain filefull path to a keychain file if an Institutional Recovery Key has been previously set up on the Volume.
The keychain must be unlocked; see security(1) and fdesetup(8) for more information.

-verify will test passphrase correctness without affecting the locked or unlocked state.

To re-lock the volume, unmount it, e.g. with diskutil unmount or diskutil apfs lockVolume.

The usual purpose of an APFS Cryptographic User is to authenticate for unlocking its APFS Volume; any of its users can do so.

An APFS Volume need not be encrypted in order to contain crypto users; other than the Disk User, they should be added before encrypting.

Types of Cryptographic Users include 'Disk' user, whose UUID value always matches its Volume's UUID;
iCloud or personal 'Recovery Keys', which store partial crypto keys and are associated with corresponding
'Recovery Users' and have fixed-constant UUID values; and
'Open Directory' users, whose UUID values match corresponding local macOS Open Directory account user GUIDs.

Supply an existing cryptographic user UUID, in which case you must supply its corresponding passphrase, or
disk (or the Disk/Volume UUID) and the corresponding passphrase of the 'Disk User'

if no users exist on this Volume, supply disk (or the Disk/Volume UUID), and a 'Disk User' will be created with a new passphrase .
Use this acquire the first such user if a volume has no cryptographics users .

The APFS Volume must be unlocked before beginning.

• stripe- Striped Volume (RAID 0)
• mirror- Mirrored Volume (RAID 1)
• concat- Concatenated Volume (ining)

From these basic types, 'stacked' or 'nested' RAID volumes can be created.
Stacked RAID sets that make use of mirrored RAID sets are fault-tolerant.
More common combinations of stacked RAID sets:

• RAID 50 - striped RAID set of hardware RAID 5 disks.
• RAID 10 - striped RAID set of mirrored RAID sets.
• RAID 0+1 - mirrored RAID set of striped RAID sets.
• Concatenated Mirror - A concatenation of mirrored RAID sets.

In addition to whole disk and partition device names, AppleRAID uses UUIDs to refer to existing RAID sets and their members.They may be specified by mount point (e.g. /Volume/raidset). Using the UUID is preferred because disk device names may change over time when disks are added, disks are removed or whenthe system is rebooted.
If RAID members have been physically disconnected from the system or are no longer responding, youmust use the member's UUID as the command argument. Messages in the system log will refer to RAID sets and their memberdisks by UUID.

RAID is not a replacement for backing up data. Backups should be always be performed on a regular basis andbefore modifying any RAID.

Concatenated volumes only support adding members. Adding a new member to a concatenated RAID set appends the member and expands the RAID volume.

CoreStorage maintains a world of virtual disks, somewhat like RAID, in which one can easily add or remove imported backing store disks, as well as exported usable volumes, to or from a pool (or several pools). This provides the user with flexibility in allocating their hardware; user or operating system data can span multiple physical disks seamlessly, for example.

Types of objects, instances of which are uniquely represented by a UUID:
• Logical Volume Group (LVG)
• Physical Volume (PV)
• Logical Volume Family (LVF)
• Logical Volume (LV)

An LVG imports one or more Physical Volumes (PVs). A PV represents a device that feeds the LVG storage space; a PV is normally real media but it can be a disk image or even an AppleRAID Set. A disk offered to be a PV must be a partition and the encompassing scheme must be GPT.

An LVG exports zero or more Logical Volume Families (LVFs). An LVF contains properties which govern and bind together all of its descendant Logical Volumes (LVs). These properties provide settings for Full Disk Encryption (FDE) (such as whether the LVG is encrypted, which users have access, etc) and other services. However, at the present time, for new LVF creation, only zero or one LVF per LVG is supported.

A Logical Volume Family (LVF) exports one or more Logical Volumes (LVs). However, at the present time, only and exactly one LV per LVF is supported.

A Logical Volume (LV) exports a dev node, upon which a file system (such as Journaled HFS+) resides.

For more information on specifying device arguments, see the DEVICES section below. CoreStorage is not a replacement for backing up your data. Backups should be always be performed on a regular basis and before modifying any CoreStorage volumes using these commands.

CoreStorage sub-verbs :