Managing Disks : Troubleshooting Disk Management & Managing Data Compression

1. Troubleshooting Disk Management

The Disk Management utility can be used to troubleshoot disk errors through a set of status codes; however, if a disk will not initialize, no status code will be displayed. Disks will not initialize if there is no valid disk signature.

The problem with disk errors is that you don't know when a disk fails or which disk failed. Disk Management can help you with this. When disks have problems or errors, status codes get assigned. Knowing what these codes mean will help you determine what the problem is and, more important, what steps need to be taken to fix the problem.

The main window of the Disk Management utility displays the status of disks and volumes. The following list contains the possible status codes and a description of each code; these are very useful in troubleshooting disk problems.

Online Indicates that the disk is accessible and that it is functioning properly. This is the normal disk status.

Online (Errors) Used only with dynamic disks. Indicates that I/O errors have been detected on the dynamic disk. One possible fix for this error is to right-click the disk and select Reactivate Disk to attempt to return the disk to Online status. This fix will work only if the I/O errors were temporary. You should immediately back up your data if you see this error and suspect that the I/O errors are not temporary.

Healthy Specifies that the volume is accessible and functioning properly.

Healthy (At Risk) Used to indicate that a dynamic volume is currently accessible but I/O errors have been detected on the underlying dynamic disk. This option is usually associated with Online (Errors) for the underlying disk.

Offline or Missing Used only with dynamic disks. Indicates that the disk is not accessible. This can occur if the disk is corrupted or the hardware has failed. If the error is not caused by hardware failure or major corruption, you may be able to re-access the disk by using the Reactivate Disk option to return the disk to Online status. If the disk was originally offline and then the status changed to Missing, it indicates that the disk has become corrupted, has been powered down, or was disconnected.

Unreadable This can occur on basic or dynamic disks. Indicates that the disk is inaccessible and might have encountered hardware errors, corruption, or I/O errors or that the system disk configuration database is corrupted. This message may also appear when a disk is spinning up while the Disk Management utility is rescanning the disks on the computer.

Failed Can be seen with basic or dynamic volumes. Specifies that the volume can't be started. This can occur because the disk is damaged or the file system is corrupted. If this message occurs with a basic volume, you should check the underlying disk hardware. If the error occurs on a dynamic volume, verify that the underlying disks are online.

Unknown Used with basic and dynamic volumes. Occurs if the boot sector for the volume becomes corrupted—for example, from a virus. This error can also occur if no disk signature is created for the volume.

Incomplete Occuts when you move some, but not all, of the disks from a multidisk volume. If you do not complete the multivolume set, then the data will be inaccessible.

Foreign This error can occur if you move a dynamic disk from a computer running Windows 2000 (any version), Windows 2008, Windows XP Professional, Windows Vista, or Windows Server 2003 to a Windows 7 computer. This error is caused because configuration data is unique to computers where the dynamic disk was created. You can correct this error by right-clicking the disk and selecting the option Import Foreign Disks. Any existing volume information will then be visible and accessible.

In addition to errors, there are some other issues that can arise when installing or configuring disks. One issue that may occur is that a disk fails to initialize when installed.

1.2. Troubleshooting Disks That Fail to Initialize

When you add a new disk to your computer in Windows 7, the disk does not initially contain a disk signature, which is required for the disk to be recognized by Windows. Disk signatures are at the end of the sector marker on the Master Boot Record (MBR) of the drive.

When you install a new drive and run the Disk Management utility, a wizard starts and lists all new disks that have been detected. The disk signature is written through this process. If you cancel the wizard before the disk signature is written, you will see the disk status Not Initialized. To initialize a disk, you right-click the disk you want to initialize and select the Initialize Disk option.

So as you have know seen, Disk Management can be a very useful tool in your computer management arsenal. If you decide to format your partition or volume using NTFS, you then receive added benefits like compression, encryption, quotas, and security. In the next section, we will start taking a looking at some of these benefits.

2. Managing Data Compression

One of the advantages of using NTFS over FAT32 is the ability to compress data. I teach IT administrators data compression and I like to refer to a well-known infomercial as an example. Have you seen the commercial where people put all of the blankets into a large bag and then hook a vacuum to the bag and suck all the air out? This is a great example of how compression works. Data compression is the process of storing data in a form that takes less space than uncompressed data.

If you have ever "zipped" or "packed" a file, you have used a form of data compression. The compression algorithms support cluster sizes only up to 4 KB, so if you are using larger cluster sizes, NTFS compression support is not available. If you have the Modify permission on an NTFS volume, you can manage data compression through Windows Explorer or the Compact command-line utility.

Files as well as folders in the NTFS file system can be either compressed or uncompressed. Files and folders are managed independently, which means that a compressed folder can contain uncompressed files, and an uncompressed folder can contain compressed files.

Access to compressed files by applications is Transparent. For example, if you access a compressed file rhrough Microsoft Word, the file will be uncompressed automatically when it is opened and then automatically compressed again when ir is closed.

Compression happens very quickly, but if, for example, you compress a 500 GB hard drive, there is no guarantee that there won't be any lag time on your machine or server.

Data compression is available only on NTFS partitions. Because of this, if you copy or move a compressed folder or file to a FAT32 partition, Windows 7 automatically uncompressed the folder or file.

Certain system files (e.g. Pagefile.sys) can't be compressed. You also have the ability to show compressed files and folders with an alternate color.

In Exercise 1, you will compress and uncompress folders and files.

To uncompress folders and files, repeat the steps in Exercise 1 and uncheck the Compress Contents To Save Disk Space option in the Advanced Attributes dialog box.

As I stated earlier, you can specify that compressed files be displayed in a different color from the uncompressed files. To do so, in Windows Explorer, select Organize => Folder And Search Options => View, Under Files And Folders, check the Show Encrypted Or Compressed NTFS Files In Color option.

In addition to compressing files and folders in Windows Explorer, you can compress the files and folders using the Compact command-line utility.

2.1. Using the Compact Command-Line Utility

The command-line options for managing file and folder compression are Compact and Expand. You can access these commands from a command prompt. The Compact command offers you more control over file and folder compression than Windows Explorer. For example, you can use the Compact command with a batch script or to compress only files that meet a specific criterion (for example, all the DOC files in a specific folder). Some of the options that can be used with the Compact command are shown in Table 1.

Another way that you can save disk space is by zipping folders. In the following section we will discuss how to save space using zipped folders.

2.2. Using Compressed (Zipped) Folders

Windows 7 also supports compressed (zipped) folders. This feature is different from NTFS compressed folders. The advantage of using compressed (zipped) folders is that it is supported on FAT32 or NTFS volumes. In addition, you can use compressed (zipped) folders to share data with other programs that use zipped files. The downside to using compressed (zipped) folders is that it is slower than using NTFS compression.

Within Windows Explorer, you create a zipped folder (or file) by right-clicking on the folder and selecting Send To => Compressed (Zipped) Folder. You create a zipped file by right-clicking on a file and selecting New => Compressed (Zipped) Folder. When you create a compressed folder, it will be displayed as a folder with a zipper.

Compression is a nice advantage to using NTFS, but another advantage is data encryption. In the following section, I will discuss the benefits to using data encryption.