Basic Disk and Dynamic Disk vs. Primary Partition and Extended Partition and Logical Partition

Question

I am trying to understand how disk partitioning works. I have learned that first you create a Partition Table, and then you partition your disk the way you are allowed in the Partition Table that you specified.

If you select the MBR Partition Table, the you can create 4 Primary Partitions, or 3 Primary Partitions and 1 extended Partiton, and the extended partition can be used to create 28 Logical Partitions (not sure about this number).

But now I am introduced to the terms Basic Disk and Dynamic Disk, what are these terms, are they Microsoft specific or something?

Answer 1

Basic Disk and Dynamic Disk, what are these terms, are they Microsoft specific?

A short summary follows. See the source link for more details.

Basic Disks

Basic disks are the storage types most often used with Windows. The term basic disk refers to a disk that contains partitions, such as primary partitions and logical drives, and these in turn are usually formatted with a file system to become a volume for file storage.

Basic disks provide a simple storage solution that can accommodate a useful array of changing storage requirement scenarios. Basic disks also support clustered disks, Institute of Electrical and Electronics Engineers (IEEE) 1394 disks, and universal serial bus (USB) removable drives.

For backward compatibility, basic disks usually use the same Master Boot Record (MBR) partition style as the disks used by the Microsoft MS-DOS operating system and all versions of Windows but can also support GUID Partition Table (GPT) partitions on systems that support it. For more information about MBR and GPT partition styles, see the Partition Styles section.

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Dynamic Disks

Dynamic disks provide features that basic disks do not, such as the ability to create volumes that span multiple disks (spanned and striped volumes) and the ability to create fault-tolerant volumes (mirrored and RAID-5 volumes). Like basic disks, dynamic disks can use the MBR or GPT partition styles on systems that support both. All volumes on dynamic disks are known as dynamic volumes.

Dynamic disks offer greater flexibility for volume management because they use a database to track information about dynamic volumes on the disk and about other dynamic disks in the computer. Because each dynamic disk in a computer stores a replica of the dynamic disk database, for example, a corrupted dynamic disk database can repair one dynamic disk by using the database on another dynamic disk. The location of the database is determined by the partition style of the disk. On MBR partitions, the database is contained in the last 1 megabyte (MB) of the disk. On GPT partitions, the database is contained in a 1-MB reserved (hidden) partition.

Dynamic disks are a separate form of volume management that allows volumes to have noncontiguous extents on one or more physical disks. Dynamic disks and volumes rely on the Logical Disk Manager (LDM) and Virtual Disk Service (VDS) and their associated features. These features enable you to perform tasks such as converting basic disks into dynamic disks, and creating fault-tolerant volumes. To encourage the use of dynamic disks, multi-partition volume support was removed from basic disks, and is now exclusively supported on dynamic disks.

Source Basic and Dynamic Disks

Answer 2

If you select the MBR Partition Table, the you can create 4 Primary Partitions, or 3 Primary Partitions and 1 extended Partiton, and the extended partition can be used to create 28 Logical Partitions (not sure about this number).

This is mostly correct. The number of logical partitions is theoretically limited only by the disk's size; in theory, you could have just under half the number of logical partitions as their are sectors on the disk, with each partition being one sector in size. In practice, this would be quite pointless. Also, there are likely to be OS-specific limits. I don't know what those limits are in Windows. The 28-logical-partition limit you cite might be accurate for Windows or it might be complete hogwash; I simply don't know the Windows limits. (I have created a disk with well over 100 logical partitions and accessed all of them in Linux, though.)

FWIW, MBR is on the way out as a partitioning system, although we may continue to see it in use on USB flash drives and the like for years to come. It's limited in quite a few ways, including a 2 TiB disk-size limit (assuming 512-byte sectors) and the awkward distinction between primary, extended, and logical partitions. The successor to MBR is the GUID Partition Table (GPT), which doesn't have the equivalent of extended and logical partitions (and therefore makes the word "primary" in "primary partition" pointless). GPT supports 128 partitions as a default value by most partitioning tools, although the standard permits that value to be raised if necessary.

Importantly, no matter what the partition table type, partitions are contiguous groups of sectors, such as sectors 2,048 to 2,664,447; you can't have a partition that has "holes" in it. This can make managing partitions awkward and dangerous, since if you use a disk for a while and then decide to delete a couple of partitions and create one new and bigger partition in its place, this might not be possible without first moving other partitions to make the free space contiguous.

But now I am introduced to the terms Basic Disk and Dynamic Disk, what are these terms, are they Microsoft specific or something?

What Microsoft calls a "basic disk" is just a disk with a conventional partition table (MBR or GPT) and filesystems stored directly on partitions -- that is, partition #1 might be FAT, partition #2 might be NTFS, etc. Any OS can find filesystems stored on a "basic disk," with the caveat that the OS must understand the partitioning system and filesystem. (Today, just about everything understands MBR, and most OSes understand GPT.)

A "dynamic disk," by contrast, uses Logical Disk Manager (LDM), which is Microsoft's proprietary logical volume management (LVM) system. LVM is more flexible than a "basic" partitioning system because it enables more flexible use of disk space. Partitions (aka physical volumes, or PVs, in LVM-speak) can be grouped together into volume groups (VGs), which in turn can be split up into logical volumes (LVs). This enables you to create a single filesystem that spans multiple disk drives. You can also add and delete LVs without worrying about their start and end points, and even if a new LV covers multiple non-contiguous ranges of sectors, which is handy if you need to frequently add and delete filesystems. Note that I'm more familiar with Linux's LVM system than with Microsoft's, so it's conceivable that Microsoft's LDM is different in some subtle way that I'm misrepresenting; but AFAIK the two are pretty similar at this level of analysis.

Microsoft tends to shift from a "basic" disk setup to its dynamic/LDM setup when you create more than four partitions on an MBR disk. This is helpful for a Windows-only system because the Windows partitioning tools are awful at handling extended and logical partitions. The problem is that LDM is a proprietary Microsoft system, so if you want to dual-boot with something else, you're likely to have problems accessing the Windows filesystems, or even installing your new OS. I'm not positive, but I'm pretty sure that Microsoft's tools are less likely to impose an LDM setup on a GPT disk.