Dirty Shutdown Explained
The term "a dirty shutdown" does not necessarily cause loss of data, but it can make access to some of not all data impossible without the help of specialist data recovery hardware and experience.
Many drives that come in for recovery are often in a failed state because of a power glitch. In the case of a system drive a dirty shutdown and cause a slight head crash or with SSD corrupt the controller.
Many times it will result in a drive asking to be formatted. But the symptom is actually not one where a "software" recovery should be used. Dust or dirt on a drive although dirty in real sense does not necessarily mean the storage platters on HDD or NAND chip memory banks are affected by dust or dirt at the physical level, but at the sector level it can cause bad blocks, bad sectors and file corruption.
Any storage device from Internal SATA, SCSI and SAS to external drives (HDD, SSD, USB, CF, SD and NAS) can be affected by an abrupt disconnect of power and require data recovery. The term degraded drive or running in a degraded state is often used but can encompass various faults from electronic , firmware, storage media bad sectors and corrupt file systems to service area module damage and lost RAID members.
In the case of servers, SAN (storage area networks) a power failure can affect databases exchange EDB and SQL even inside a VM /VHD or Lun and the term dirty shutdown can apply to the corruption or loss of tables or data within the database or virtual volume, virtual machine or virtual drive.
So if you have a dirty shutdown and lose access to critical data R3 can often restore all lost data, repair damaged files or corrupt virtual machines and virtual disks as well as recovering the physical disk.