HFS+ Healing Algorithms in Disk Drill

Disk Drill is a powerful HFS+ data recovery tool, and in addition to regular file recovery from HFS+ partitions, it can actually make an attempt to recover the original partition itself after it was lost or damaged. All available data recovery methods related to HFS+ are merged into “HFS+ healing” family in Disk Drill. All Disk Drill’s recovery options can be previewed for free in Disk Drill Basic, so you can ensure your data recoverability before considering going premium. In general, there are 4 major cases when Disk Drill may help recovering an HFS+ partition:

1. Partition is intact but has a local defect when reading from existing file system – refer to “Allocate existing file system data” recovery option. There’s a reasonable chance the lightly defected file system that is not available to regular macOS disk management tools will be discovered and restored by Disk Drill through this option. Note, just running the universal scenario with the “Recover” button will NOT include allocation of existing data. This algo needs to be selected manually.
2. Light damage, “Rebuild” option. This algorithm is effective when HFS+ partitions are lightly damaged, and the boot sector is still in a relatively good condition. That’s exactly when Disk Drill displays the Rebuild button instead of a regular Recover. If you proceed with rebuilding the HFS+ catalog, Disk Drill will use the data in the boot sector to locate other meta-information about files and folders and tolerantly read it.
3. Medium damage, “Scan for lost HFS+ partition”. In case the boot sector is damaged, but there’s a backup copy of its contents on the drive, you can proceed with Scan for lost HFS+ partition. Keep in mind, Disk Drill goes through all recovery methods available for your particular drive automatically, so generally you don’t need to choose a specific method, unless you want to run only one. The unified “Recover” button will do everything to ensure all data recovery methods were applied. In this case Disk Drill will read the backup copy and restore meta-information from it. Sometimes this helps recover HFS+ partitions after formatting them into FAT/ExFAT or other non-HFS standard.
4. Critical damage, “HFS+ Extraction”. If both boot sector and its backup copy are damaged, then Deep Scan is definitely your major choice of action. During deep scanning while Disk Drill is reconstructing your deleted files, it also automatically searches for your lost HFS+ meta-information, and if any known signatures of the partition structure are found, it will attempt to reconstruct the whole partition for you. In this case you will see a new virtual partition in the drives list when you get back to the initial screen of Disk Drill. The files from the found partition will also be listed among the scanning results.
5. All partition information destroyed. There’s not much you can do when the folder structure is gone completely. A good sample for this case will be re-formatting an HFS+ partition back to HFS+, like this: HFS+ formatted into FAT32, and then back to HFS+ again. Obviously, the original HFS+ is gone for good now. Disk Drill will not be able to recover the original partition structure in this case.