LastMountedVersion: 10.0, last mount by Mac OS X. Searching backwards for the Alternate Volume Header. Hfsprescue -find-avh Įxample: Stop after the first HFS+ Alternate Volume Header.Ĭommand: hfsprescue -find-avh /dev/sdb -first The resultof the search is stored in ' hfsprescue-data/find-avh.log'. The search for the Alternate Volume Header goes from the end of the hard disk to the beginning. When you know the location of the Alternate Volume Header, the block size and total blocks, then its possible to calculate the partition start. The Alternate Volume Header is a backup of the Volume Header and is stored 1024 bytes before the end of the partition. See here.Įxample: hfsprescue -extract-vh /dev/sdb 409642 In combination with ' -s3' and ' -one-file'.Įxample: hfsprescue -s3 /dev/sdb -o 209735680' The partition start offset is ' 209735680'. LastMountedVersion: H+Lx, last mount by Linux. *** Stop searching after the first Volume Header has been found.
Hfsprescue -find-vh Įxample: Show only the first HFS+ Volume Header.Ĭommand: hfsprescue -find-vh /dev/sdb -first The result of the search will be logged in the file ' hfsprescue-data/find-vh.log'. When you use ' -o ' then the search begins at the offset and skips the bytes before. If you need more details during the search process then use the ' -v' verbose parameter. When the last mount of the partition has been done by another OS, then use ' -f' to ignore the This field is set by the operating system that mounts the partition. Output to the first detected HFS+ Volume Header.Ī valid HFS+ Volume Header criteria of hfsprescue is the
You can use the ' -first' parameter to limit the Partition on the drive, then the first hit should be the right one. This means that hfsprescue will report a few hits. A HFS+ file system has a backup of the Volume Header (the Alternate Volume header). One solution to get the partition start offset is to find the HFS+ Volume Header with the ' -find-vh' When you lost the partition table or you are working with a hard disk image then it's required to know the start offset of the partition The Volume Header has also important information like the location and size of the Extents Overflow File. Finding the Volume Header is a good way to find the partition start. The location of the Volume Header is 1024 bytes after the partition start. Both can be used to find the start of a partition. The Volume Header and Alternate Volume Header have important information about the HFS+ file system. More advanced disk format compatible with Mac OS 8.HFS+ Rescue - Find the HFS+ Volume Header or Alternate Volume Header and the partition start offset Homeįind the HFS+ Volume Header or Alternate Volume Header and the partition start offset Volumes, especially if they contain numerous small files, accumulate In this case, no matter how small a file is, it will always beĪllocated at least 16KB of space. Thus, the size of each allocation block of a 1GB (i.e., 1024MB)ģ2 * 512 is approximately 16KB (or 32 512-byte logical blocks) Minimum file size, use this formula: Volume size (in megabytes ) * 2000 = Aī * 512 = minimum file size (rounded to the nearest 512-byte logical block) To determine the allocation block size of a volume, and thus its The larger a volume is, the larger its minimum file size will be.The absolute maximum number of files on a volume is 65,356. An allocation block can store information for only one file, so.Regardless of its size, a volume cannot have more than 65,356Īllocation blocks. Because HFS uses a 16-bit address to store and locate data, The size of an allocation block (whichĬonsists of one or more logical blocks) depends on the size of the Logical blocks, the basic storage units of a drive, areĪlways 512 bytes. There are two kinds of blocks on an HFS volume: logical andĪllocation. Each folder may contain up toģ2,767 files volumes on recent OS versions and computer models may be HFS supports a directory (i.e., folder) tree and much larger volumes Kilobyte (KB) floppy disks used in the Macintosh 128K and 512K models, Unlike MFS, which was designed for the 400 HFS (Hierarchical File System), also known as the Macintosh Standardįormat, is a volume format introduced in 1985 to replace MFS Information here may no longer be accurate, and links may no longer be available or reliable. This content has been archived, and is no longer maintained by Indiana University.