5.5-5.6 File Systems, MBR & GPT Partitions, & Disk/Volume Status in Disk Management Facts

Windows supports two different kinds of disks: basic and dynamic. The disk type controls characteristics about how partitions and volumes are defined.

*1) Basic disks* use primary and extended partitions. -Each physical disk can have up to four primary partitions or three primary partitions and one extended partition. -Logical drives are defined within an extended partition. You can have up to 24 logical partitions on an extended partition. The extended partition can be divided into multiple logical drives. -You must create a logical drive in an extended partition before you can format and store data (the logical drive, not the partition is the storage unit). -Basic disks are supported by all operating systems. -A basic disk only supports volumes made up of contiguous disk space. *Basic disks store partition information in a portion of the master boot record (MBR) known as the partition table.* -The partition table has room for up to four partition entries (hence the limitation on the number of primary partitions). -When an extended partition is used, one of the four entries points to an extended boot record (EBR). The EBR is located within the extended partition and contains information about the logical drives within the extended partition. *2) Dynamic disks* -Volumes on dynamic disks are like partitions and logical drives on basic disks. -Dynamic disks support up to 128 volumes. *Dynamic disks support volumes that use discontiguous disk space.* -Simple volumes contain disk space from a single hard disk (either contiguous or discontiguous space). -Spanned volumes contain disk space from multiple hard disks, grouped together into a single logical volume. -Dynamic disks store partitioning information in a hidden database on all dynamic disks in the system.

GPT partitions are a new standard that is gradually replacing MBR partitions. GPT is associated with UEFI. GPT stands for GUID Partition Table. It's called GUID Partition Table because every partition on the drive has a globally unique identifier or GUID. That means that each partition worldwide would have its own unique identifying number.

*A GPT disk:* -Can be basic or dynamic disks -Supports up to 128 partitions depending on the space allocated for the partition table. There is no need for extended and logical partitions. -Can support between 8 and 9.4 zettabytes depending on the sector size -Stores multiple copies of the partition table across the disk, so it's much more robust and can recover if the data is corrupted -Stores cyclic redundancy check (CRC) values to check that its data is intact. If the data is corrupted, GPT notices the problem and attempts to recover the damaged data from another location on the disk. MBR has no way of knowing if the data is corrupted. You would only see that there was a problem when the boot process failed or the partitions vanished. -Include a *protective MBR*. The protective MBR sees the GPT drive as a single partition that extends across the entire drive. So if you try to manage a GPT disk with an old tool that can only read MBRs, it will see the GPT disk as a single partition that extends across the entire drive. The protective MBR makes sure that the old tools don't mistake the GPT drive for a non-partitioned drive and overwrite all your data.

Directory (AKA folder)

*A directory (folder) is a container in a volume that holds files or other directories. It is used to logically sort and organize data to keep related files grouped together. Most operating systems use a hierarchical filing structure.*

File

*File is a one-dimensional stream of bits treated as a logical unit. They are the most basic component that a file system uses to organize raw bits of data on the storage device itself. The file name is made up of the directory path plus the file name. An extension can also be added to the filename to identify the file type and the program used to create, view, and modify the file.*

Formatting (File system)

*Formatting is the process of preparing a partition to use a specific file system.* *Be aware of the following facts regarding formatting:* -When you format a disk, you identify the file system type and identify the cluster size used to store data. -Reformatting removes the existing file system and replaces it with the new file system type. -Reformatting a drive deletes all existing data. -If your system or disk supports multiple operating systems, be sure to select a file system supported by all necessary operating systems. -NTFS is not recommended for disks smaller than 10 MB. -When using NTFS on removable devices, you must use Safely Remove Hardware before removing the flash device to prevent file corruption.

Partition (File system)

*Partition is a logical division of a storage device associated with a hard disk drive. Multiple partitions can be assigned to a single device in which case a drive letter is assigned to represent each partition. Multiple letters do not always mean that there are multiple devices, just multiple partitions.* *Some reasons why you may consider partitioning your hard drive are:* -Assigning the boot system to a different partition than application and data files can help many computers run more smoothly and minimize damage in a system crash. -It is sometimes necessary or useful for the swap file to be stored on its own partition. -Some operating systems can't run on a large partition. Creating a separate partition for your operating system can help it run properly. -Assigning log files to be stored on distinct partitions can help minimize the effects of a system crash due to excessively large log files. -Distinct operating systems can be assigned to run on assigned partitions to allow a dual boot system setup. *Unallocated space* is space on a partition that has not been assigned to a volume. You cannot store or read data in unallocated space.

Volume (File system)

*Volume is a single accessible storage area within a file system. A volume can encompass a single partition or span across multiple partitions depending on how it is configured and what operating system you are using. Volumes are identified by drive letters.*

For Windows systems, you will likely choose NTFS over FAT for hard drives to take advantage of additional features not supported by FAT such as:

-The ability to format larger partition sizes in Windows -Smaller cluster sizes for more efficient storage with less wasted space -File and folder permissions to control access to files -Encryption to hide the contents of a file -Compression to reduce the amount of space used by files -Disk quotas to restrict the amount of disk space that files saved by a user can use -Volume mount points that allow you to map disk space on another partition into an existing volume

Be aware of the following when managing partitions and volumes:

-Use *Disk Management or DiskPart* to create, format, and manage partitions and volumes. You access Disk Management on Windows systems through Computer Management. You access DiskPart from the command prompt by entering cmd. -Basic and dynamic disks use the same hardware, but different partitioning methods. *You can convert a basic disk to a dynamic disk without losing data in existing partitions.* -Existing basic volumes and logical drives in the extended partition are converted to dynamic volumes. -You must reboot the system to complete the conversion if the disk contains the boot or system volume, or if the volume includes the pagefile. -To convert from a dynamic disk to a basic disk, you must delete all existing volumes. *Active partition* identifies the partition that contains the operating system (or the program that loads the operating system) used to start the computer. -You can have only one active partition at a time. -The extended partition or a logical drive on the extended partition cannot be set to active. -You cannot install the operating system on a dynamic disk. You can, however, upgrade a basic disk containing the operating system to a dynamic disk after installation. -When you shrink a partition, unmovable files (e.g., the paging file or the shadow copy storage area) are not automatically relocated and you cannot decrease the allocated space beyond the point where the unmovable files are located. If you need to shrink the partition further, check the Application Log for Event 259, which identifies the unmovable file. Next, move the paging file to another disk, delete the stored shadow copies, shrink the volume, and then move the paging file back to the disk. -You can shrink primary partitions and logical drives on raw partitions (those without a file system) or partitions using the NTFS file system. -To shrink a partition, you must be a member of Backup Operators or Administrators (or equivalent) to complete this process.

When implementing GPT partitioning, be aware of the following:

-You'll probably want to use GPT when setting up a drive; however, if you need compatibility with old systems, like the ability to boot Windows off a drive on a computer with a traditional BIOS, you'll need to use MBR. -Windows can only boot from GPT on UEFI-based computers running 64-bit versions of Windows 7, 8.x, 10, and the corresponding server versions. All versions of Windows 7 and later can read GPT drives and use them for data, but they cannot boot from them without UEFI. -Because Windows 7 does not support UEFI on 32-bit platforms, you cannot boot from a GPT partition on Windows 7. -Linux has built-in support for GPT. Apple's Intel Macs no longer use Apple's APT, or Apple Partition Table, scheme but use GPT instead.

Unavailable status & Unreadable status

1) Unavailable status indicates that errors have occurred on physical or dynamic disks. 2) Unreadable status indicates a hardware failure, I/O errors, or other corruption but might also be caused by a delay in reading the disk in Disk Management. Try rescanning the disk to see if the status changes; if not, troubleshoot the hardware or disk problem.

File system

A means for organizing and storing data and information on a storage device. The file system and the operating system work together to ensure data availability, integrity, and accessibility. There are 4 main components of a file system.

Extended File Allocation Table (ExFAT, AKA FAT64) File system

A special file system that is designed to support large flash drives. Using NTFS on flash drives is usually not a good idea due to its high overhead and risk of corruption if the device is not stopped properly prior to removal. However, many flash drives exceed the 32 GB limit discussed above. Microsoft introduced native ExFAT support in Windows 7 to allow large removable flash storage devices to continue to use a FAT-type file system.

Failed status

Failed status shows for a volume that cannot be started, such as when the disk is damaged or the file system is corrupt. Make sure the disk is on, then try reactivating the volume. If that doesn't work, then you likely have data loss.

Foreign disk

Foreign disk is a dynamic disk that was created in one system and moved to another system. When you first add the disk to a different system, the partition information for the disk must be updated to reflect all dynamic disks in the current system. Import the disk to make it available in the new system.

Formatting status

Formatting status is shown for volumes during the formatting process. After formatting, the status for the volume changes to Healthy.

Healthy or Online status

Indicates that the disk is turned on and can be accessed. The volume on the disk is valid and has no errors.

Initializing process

Initializing process shows while a disk is being converted from a basic disk to a dynamic disk. After the conversion, the status for the volume changes to Healthy.

Missing or Offline statuses

Missing or Offline statuses show when a dynamic disk has failed, been removed, or turned off. If the disk is turned off, turn it back on, then reactivate the disk. If the disk no longer exists, then delete the disk from Disk Management.

No Media status

No Media status shows for an optical or removable media drive that does not contain a valid disc. This disk status only applies to CD-ROM, DVD-ROM, or removable disks.

Not Initialized or (Unknown status)

Not Initialized or Unknown status indicates a disk without a valid master boot record or partition table (either missing or corrupt). To correct the problem, initialize the disk. If the partition table is invalid, use third party tools to try to recover the partition table.

Online (Errors) status

Online (Errors) status indicates that I/O errors have been detected on a dynamic disk. To correct the problem, try reactivating the disk.

Unallocated status

Unallocated status shows for portions of a disk that have not been assigned to a partition or a volume.