"File Slack" refers to the data between the last byte of the file and the end of the cluster. It usually contains whatever bit pattern the OS uses to represent unallocated memory. Show
"Drive Slack" refers to clusters that have been deallocated but not overwritten. It can also refer to unallocated space that no longer falls within a partition boundary. "RAM Slack" -- I have never heard this term before. Googling this, all the resources I find seem to be quoting or deriving from a book titled "Cyber Forensics: A Field Manual For Collecting, Examining, and Preserving Evidence of Computer Crimes" by Albert J. Marcella, Jr. and Doug Menendez. I read the chapter where the term is used. Even though it was copyrighted in 2010, it makes reference to the way DOS and Windows 95/98 did things. That hasn't been relevant for over a decade. I could be reading it out of context though. Either way, this book appears to be the source of the term.
This is correct in the case of legacy drives and 4K "advanced format" drives. The sector size is truly 4KB on 4K "native" drives, so there is a 1:1 correlation between sectors and clusters for those drives.
Also correct.
This is incorrect. Windows does not write in blocks; only clusters. It will write data at any arbitrary size, but they will be in multiples of the cluster size (usually 4KB).
The only time Windows cares about sectors/blocks is when an LBA address must be calculated. The low-level disk driver does this, not the filesystem driver. It's actually very inefficient to do reads/writes in 512-byte chunks. It works against the drive's internal hardware caches. Doing a
Also incorrect. Windows will write whatever is in the buffer. Almost every application (including the filesystem driver) allocates fresh memory from the heap when writing to the output buffer. When an application allocates memory, it does so in pages, which are (guess what!) 4KB in size. Unallocated memory is usually represented by a repeating bit pattern (not 00 or FF), so that is what will be written to the end of the cluster if it's not full. In cases where the application's output buffer is a modified copy of its input buffer, the slack will contain whatever data the input buffer had in it.
Also incorrect. Windows will always do a full-cluster commit even if there's only 1 byte of changed data. It is true that deallocated clusters have whatever data was in them before. Windows does not bother with zeroing out deallocated clusters. But none of this takes place at the sector level. 4KB is a magic number. Memory pages are 4KB. I/O buffers are 4KB. Sectors are 4KB now. Even the drive's hardware is optimized for I/O requests that are 4KB (or some multiple thereof). All modern operating systems work this way (Windows, Linux, and OS X). The only exceptions to the rules above are applications that have the disk open for raw access. They completely bypass the operating system's API calls for doing writes. You only see this with low-level recovery and forensic tools because such applications do not benefit from all of the optimizations you get with buffered I/O.
Homepage Accessibility links
BBC Account Notifications
More menu Search Bitesize Search Bitesize
BITESIZE
GCSE Operating systemsAn operating system is software that manages computer hardware and software. It supplies an interface for the user and important utilities for managing the computer. Part of Computer Science Software
quiz
UtilitiesThe OS uses applications called utilities which allow the user to manage the computer. There are many different utility programs and they may vary across operating systems. They are often accessed via a special menu or control panel in the OS. Maintenance utilitiesThese include:
Security utilitiesThese include:
next GCSE Subjects
What type of storage drive contains multiple spinning platters?Hard drives typically have several platters which are mounted on the same spindle. A platter can store information on both sides, requiring two heads per platter.
What file system supported by Windows can be used for volumes and drives that do not hold the Windows installation?Correct. NTFS file system is supported by Windows and was designed to replace FAT32 file system. NTFS supports encryption, disk quotas, and file and folder compression. NTFS is also required for the volume on which Windows is installed.
What is a user profile and what are the two general items it consists of?A user profile is a login on a computer that can make your files, settings, and privileges be separate from others. On a user profile the two things are the users files, and the users settings.
What is a snapshot of the system setting and configuration called?A system restore point is an image of the system configuration and settings in the Windows Registry that helps in restoring the system to an earlier date when the system was running perfectly.
|