DisksNotes

DisksNotes

This section includes important information about basic and dynamic disks, RAID, drive letters , drive paths, disk quotas, and disk defragmenting.

Basic Versus Dynamic Disks

Disks must be either basic or dynamic; they can't contain a mixture of partitions and volumes . However, your computer can have a combination of basic and dynamic disks in its disk subsystem.

Dynamic disks can't be accessed by MS-DOS or earlier versions of Microsoft Windows. For example, if you physically move a dynamic disk from a W2K Server to an NT 4.0 Server computer, the new system will not be able to use it.

Dynamic storage is not supported on removable media. Only primary partitions are allowed on removable media.

You can't reinstall WS2003 on a volume that has been created from unallocated space on a dynamic disk. This is because under the hood there are really two types of volumes:

Volumes created from partitions when a basic disk was upgraded to a dynamic disk: This type of volume has a partition table similar to that in a partition of a basic disk, and it can't be extended.
Volumes created after conversion of unallocated space on a dynamic disk: This type of volume has no partition table and therefore can't be recognized by the Setup program of WS2003.

When you add a new disk to a computer, the disk is automatically configured as a basic disk. If you are using dynamic storage on your other disks, convert the new disk to dynamic after it has been recognized by the system.

You can't upgrade basic disks to dynamic when the sector size exceeds 512 bytes.

RAID

The system and boot partitions can't be part of a volume set, stripe set, or stripe set with parity. They can be part of a mirror set, however, which is a good way of providing fault tolerance for these partitions. However, hardware RAID can be used for system and boot partitions.

You can't extend a simple volume formatted with FAT or FAT32; you can do so only with NTFS.

You can't mirror a spanned volume that uses multiple physical disks; you can do so only with a simple volume that exists on a single physical disk.

You can't "unextend" a simple volume once you have extended it, and you similarly can't do so with spanned and striped volumes.

You can't extend a simple volume once you have mirrored it.

You can't extend or mirror a RAID-5 volume.

You can't extend the System or Boot volume, so make sure you give these volumes enough space when you install WS2003 on a machine.

Resynchronization is the process whereby a stale copy of a mirrored volume is brought up to date. Stale mirrors typically occur when one disk in a mirrored volume is temporarily disconnected or down. Mirrored volumes on dynamic disks are resynchronized automatically. If you have an older mirror set on your system (by virtue of installing WS2003 on an existing NT Server system), right-click on the volume and select Resynchronize Mirror to manually force resynchronization.

Breaking a mirror separates it into two simple volumes that are no longer fault-tolerant. Removing a mirror turns one half of a mirrored volume into unallocated space and the other half into a simple volume.

Drive Letters

Changing drive letters incautiously can drastically affect whether MS-DOS or legacy Microsoft Windows applications can continue running on the system.

Drive letters can't be changed for the System or Boot partitions.

You can't format a partition or volume that doesn't have either a drive letter or a mount point assigned to it.

Drive Paths

Partitions, volumes, and logical drives can be assigned multiple drive paths, but only one drive letter.

Assigning a drive letter or mounting a folder to a partition or volume doesn't make the partition or volume available on the network: you still need to share it.

To edit a drive path, you must first remove the path and then assign a new drive path to the partition or volume.

Disk Quotas

You should not set disk quotas on the system partition since problems may result if the operating system runs out of space. This occurs if you try to install new applications while logged on as a user who doesn't have administrative privileges. If you install these applications while logged on as an administrator, quota settings are ignored as members of the Administrators group aren't limited by any disk quota settings.

File compression is ignored when disk quotas are calculated. Compressed files are charged to the quota according to their uncompressed size.

Enabling disk quotas on a volume creates a small amount of overhead. As a result, filesystem performance may degrade slightly.

Disk quotas can be assigned only to users, not to groups.

If a user tries to write to disk when her disk space has been exceeded, the error message "insufficient disk space" appears.

The quota limit is displayed for users as the capacity of the drive on which quotas have been configured. For example, if a quota limit of 25 MB is set on G : drive, any user who selects G : drive in Windows Explorer or My Computer sees that G : has a capacity of only 25 MB, regardless of the size of the physical disk on which G : exists.

Note that enabling and setting quota limits on a disk for all users doesn't actually divide the disk into segments of fixed size for each user. For example, user one and user two would both read the capacity of G : drive as 25 MB. If user one placed a 5 MB file named stuff.dat into the root of G : drive, the drive would show 5 MB of used space and 20 MB of free space. If user one then logged off and user two logged on, user two would also see the stuff.dat file in the root of G : drive, but this drive would display 0 bytes of used space and 25 MB of free space. So it's not enough to set quotas to manage disk space for users. You also have to create home folders where they should store their work and set appropriate permissions on these folders.

If a user finds he is reaching his limit and decides to delete files on the quota-enabled disk, he may discover after deleting that he still has the same space usage on the disk. This is because when a user deletes a file for the first time on a volume or partition, by default WS2003 creates a new Recycle Bin on the drive and simply moves the deleted files to the Recycle Bin, resulting in no net gain in free space. You can prevent this from occurring by configuring the Recycle Bin properties to restrict which drives can have a Recycle Bin on them.

You can sort the users in the Quota Entries window by using View Arrange Items and then specifying the sort field. A good choice would be to sort by status to see quickly which users have exceeded their quotas, which are in a warning state, and which are still within limits. A quicker alternative is to click on the column title for the field you want to sort by.

You can copy quota entries from one quota-enabled volume to another in one of two ways:

Use Quota Export on the initial volume's Quota Entries window to save the settings to a file, then use Quota Import on the destination volume's window to import the saved settings.
Drag selected quota entries from one Quota Entries window to the other.

You can generate a report of disk quota usage by opening the Quota Entries window for a volume, choosing Edit Select All, and dragging the highlighted entries into the window of a program such as Microsoft Excel or even Microsoft Word.

Disk Defragmenter

Use Disk Defragmenter during times of light or no usagefor example, late at night.

You can safely defragment the system and boot volumes, but do so when activity is light.

System files can't be defragmented using Disk Defragmenter. This includes the Master File Table (MFT), located at the beginning of each NTFS volume, and the paging file. Any other open files on the system are also not defragmented, so it is a good idea to close all running applications and files that may be open prior to starting defragmentation.

The key figure in an analysis or defragmentation report is the Average Fragments Per File, which should be as close to 1 as possible. A value of 1.25, for example, would indicate 25% defragmentation on the volume.

Always analyze a volume before defragmenting itanalyzing takes much less time and can determine whether defragmentation is really useful or not.

Volumes to which frequent file changes are written should be defragmented more frequently. An example would be the volume on a member server where users' home folders are stored.