Aug 10, - Comments So you forgot your Mac password… uh oh.
Do not dump back up or archive this file 1 File may not be changed 2 Writes to file may only append 3 Directory is opaque see below fileMode BSD file type and mode bits.
Note that the constants from the header shown below are in octal base eightnot hexadecimal.
Mac OS X does not use this optimization. If the sticky bit is set for a directory, then Mac OS X restricts movement, deletion, and renaming of files in that directory. Files may be removed or renamed only if the user has write access to the directory; and is the owner of the file or the directory, or is the super-user.
For directories, and most files, this field is unused and reserved. When used, this field is used as one of the following: See the Hard Links section for more information. Mac OS 8 and 9 treat the permissions as reserved. A union mount presents the combination union of several file systems as a single file system.
Conceptually, these file systems are layered, one on top of another. If a file or directory appears in multiple layers, the one in mac fsck no write access top most layer is used. All changes are made to the top most file system only; the others are read-only.
The default user and group IDs are 99, but can be changed at the time the volume is mounted. This default ownerID is then subject to substitution as described above. This means that files created by Mac OS 8 and 9, or any other implementation that sets the permissions fields to zeroes, will behave as if the "ignore ownership" option is enabled for those files, even if "ignore ownership" is disabled for the volume as a whole.
Two such structures -- one for the resource and one for the data fork -- are stored in the catalog record for each user file.
In addition, the volume header contains a fork data structure for each special file. An unused extent descriptor in an extent record would have both startBlock and blockCount set to zero. For example, if a given fork occupied three extents, then the last five extent descriptors would be all zeroes.
For HFSPlusForkData structures in a catalog recordthis field was intended to store a per-fork clump size to override the default clump size in the volume header. As of Mac OS X version See the Hot Files section for more information. This array holds the first eight extent descriptors. If more extent descriptors are required, they are stored in the extents overflow file.
The volume header -- analogous to the master directory block MDB for HFS -- contains information about the volume as a whole, including the location of other key structures in the volume.
The implementation is responsible for ensuring that this structure is updated before the volume is unmounted. A copy of the volume header, the alternate volume header, is stored starting bytes before the end of the volume. The implementation should only update this copy when the length or location of one of the special files changes.
The alternate volume header is intended for use solely by disk repair utilities. The first bytes and the last bytes of the volume are reserved. The first bytes are reserved for use as boot blocks; the traditional Mac OS Finder will write to them when the System Folder changes. The boot block format is outside the scope of this specification.
It is defined in Inside Macintosh: The last bytes were used during Apple's CPU manufacturing process.
The allocation block or blocks containing the first bytes reserved space plus volume header are marked as used in the allocation file see the Allocation File section.
Also, in order to accommodate the alternate volume header and the reserved space following it, the last allocation block or two allocation blocks, if the volume is formatted with byte allocation blocks is also marked as used in the allocation file.Great post!
Forwarded this to my HelpDesk. One missing detail for portable Macs with no signs of life (no chime, no fan, etc) Try an SMC reset.
Aug 07, · How to use Single User Mode and fsck to repair a disk.
Boot the Mac into Single User Mode by holding down Command+S during system boot after you hear the boot chime, you know you will have successfully entered Single User Mode because you will see a bunch of white text on a black background scroll by; When the Single User boot sequence has finished, you’ll find a small command .
Reset Your SMC & PRAM. My next course of action, now that I could get the Mac to wake up, was to reset the SMC and PRAM How To Reset Your Mac's SMC & PRAM – And Why How To Reset Your Mac's SMC & PRAM – And Why Sometimes your Mac will act strange for no apparent reason, and if a restart doesn't work, sometimes you'll need to reset the SMC and PRAM.
HFS Plus or HFS+ is a file system developed by Apple Inc. It replaced the Hierarchical File System (HFS) as the primary file system of Apple computers with the release of Mac OS HFS+ continued as the primary Mac OS X file system until it was itself replaced with the release of the Apple File System (APFS) with macOS High Sierra in HFS+ is also one of the formats used by the .
Mac OS X has a built-in disk diagnostic and repair program called fsck or file system consistency check. Unlike Disk Utility, which can only verify the current startup disk, fsck . HFS Plus Basics. HFS Plus is a volume format for Mac OS.
HFS Plus was introduced with Mac OS HFS Plus is architecturally very similar to HFS, although there have been a number of changes.