# Windows NT Server 4.0 Notes
Module 6: Managing Partitions
Background
There are two kinds of partitions: Primary Extended Primary Partitions There can be up to four primary partitions on one hard disk or three if there is an extended partition. On RISC-based computers the primary partition must be FAT and at least 2 MB in size. Some O/Ss like MSDOS 5.0 can recognize only ONE primary partition per disk Extended partitions An extended partition is a method of getting around the four partition limit, and for configuring a hard disk into more than four logical volumes. There can be only one extended partition on a hard disk. (so it's important that you use all of the remaining space available) Unlike primary partitions these extended partitions are not formatted and are not assigned drive letters. The extended partitions are divided into segments that are treated as a logical drive and formatted with a file system.
Volume Sets
> By creating a volume set you can combine the unformatted free space from 2 through 32 areas, located on one or more physical disks. After it has been created, it must be formatted. Note that portions of disk space in a volume set cannot be separately partitioned without losing the whole volume set. A volume set CAN combine areas from different types of hard disks like SCSI, ESDI or IDE. A volume set does not give the system better or worse performance. This is because the data is being written to one disk only until it is full, then the system will continue on the next. ðdisks are always accessed one at a time.
> Note: Volume sets can be either FAT or NTFS Volume sets can be created on one single drive.
Stripe Sets
> Stripe sets can be created from at least two physical drives (but maximum=32) They can combine areas on different types of drives such as SCSI, EDSI and IDE The data is written evenly across all physical disks on one row at a time. Windows NT writes data to those rows in 64 KB units. The free spaces on all disks MUST all be the same size ð The amount of disk space used in a stripe set is the smallest amount of free disk space on one of the stripe set member's times the number of disks included in the set.
> Note: If the system has hard disks that can be accessed simultaneously, concurrent I/O commands can be issued simultaneously on all disks and therefore increase write speed, b/c NT can do 4 things at once. Unlike a volume set, a stripe set cannot be extended. Disk Administrator will create a stripe set of parts that will all be nearly the same size.
Troubleshooting Volume Sets and Stripe Sets All these points apply to BOTH Volume and Stripe Sets READ AND REMEMBER! You cannot reclaim a portion of disk space used in a volume set or stripe set for other purposes without Losing the entire volume set or stripe set and all of the data stored on it. NT system and boot partitions cannot reside in a volume set or stripe set. Win95 and Dos can not access information in a volume set or stripe set. Volume sets or stripe sets does not provide fault tolerance. In fact, volume sets spanning multiple hard disks are more susceptible to failure. Comparing a Stripe Set to a Volume Set:
| Stripe Set | Volume Set
Can it be created on one physical disk? | No | Yes
Can it contain the system or boot partition? | No | No
Maximum number of combined areas | 32 | 32
Should the size of the combined areas be the same? | Yes | No
Can areas be combined on different types of hard disks (SCSI, EDSI and IDE)? | Yes | Yes
Is the area on one disk filled before writing to another? | No (This means it's faster) | Yes
Can it improve I/O performance? | Yes | No
Can you extend the size? | No | Yes, only if it is NTFS
Creating, Formatting, Extending and Deleting Volume Sets or Stripe Set
All free space created with a volume set must be formatted with the same file system To create volume set or stripe set, hold CTRL key can click Create Volume Set or stripe set option in Partition menu, then choose Commit Change Now from Partition menu. Same is true for extending volume set. You can extend a volume set ONLY if it is NTFS. You cannot extend stripe set. When a volume set is created or extended, or when a stripe set is created, it is necessary to restart the computer. However, primary and extended partitions can be removed, reconfigured, and formatted without restarting the computer. Additional Hard Disk Considerations The number of physical hard disks that can be connected to a computer depends on: System configuration. (i.e. 2 x IDE x2= 4 total) Number of devices that can be connected to an IDE disk controller or SCSI bus controller (7 total) Number of disk controllers in a computer. Removable Media Removable media can have only one partition and that must be primary partition. Removable media can not be part of a volume set or stripe set, and cannot contain a system partition or boot partition. NT can format removable media as either FAT or NTFS. However, if the removable disk is formatted as NTFS, the computer must be shut down and restarted to change disks.
Using Disk Administrator
Use Disk Administrator to manage, partition, and format hard disks. You can create stripe sets, volume sets and mirroring with it. Disk Administrator can be thought of as a graphical Windows NT version of the MS-DOS fdisk utility. It will want to write a signature to the disk the first time it is recognized by Disk Administrator. The signature will be recognized (by Disk Administrator and by the Windows NT fault tolerance driver "ftdisk.sys") when the disk is moved to another controller or if its identification has changed. Fault Tolerance menu is included only on Windows NT Server Disk Administrator and it can only be administered on computers running Windows NT Server. Make sure you know how to use the Disk Administrator. ### Create, format, delete partition and mark partition active Create partition by selecting free space, from Partition menu, click create. Format partition by typing format d:/fs:fat|ntfs or use Format option on tool menu. Deleting partition: You can not delete system or boot partition from within NT. You can do so either booting to another OS such as MS-DOS, then delete or Booting from NT setup disk, select system partition and then press "d". You can not delete partition containing an open file. This includes the partition where pagefile.sys resides.
Marking Partitions as Active
In order for OS to start, the partition containing the startup file must be marked as active. Active partition must be primary partition containing the system boot files. Only one partition can be marked as active. When a system partition is marked active, the active designation of any other partition is removed. Note: If you want to use an OS, such as UNIX or OS/2, that is located on a partition other than the partition currently marked active, you must mark the system partition of the other operating system as active. Then shut down and restart the computer.
Partition Renumbering and Boot.ini editing
When you create a new primary partition, it will be assigned a lower number than any logical drive on an extended partition on any drive. (see below) Then the logical partitions are renumbered. So, if boot partition resides on an extended partition that was subsequently renumbered , then the Boot.ini file must be manually updated so that it points to the boot partition; other wise, windows NT will not start.
Automatic Assignment of Drive Letters by NT
Until Disk Administrator is run for the first time, NT dynamically assigns drive letters using the following procedure: 1st primary of each drive-->logical drive of each drive-->remaining primary partitions of each drive. After Disk Administrator is run for the first time, it assigns static drive letters to partitions. Starting with Disk 0, the first primary partition on each disk is assigned a consecutive drive letter, beginning with the active system partition as drive C. Then, starting with Disk 0, logical drives on each disk are assigned the next consecutive letter(s). The remaining primary partitions on each disk with unassigned partitions are each assigned a letter. Reassigning Drive Letters You can reassign drive letter by choosing Assign Drive Letter from Tool menu. A partition can be statically assigned any letter that isn't already in use by a local device. BUT be careful not to change the drive letter of the system partition b/c many programs reference the C:\ drive. Note: All drive letter modifications made with Disk Administrator can be done without rebooting the computer. However if the selected partition contain NT system files, you need to restart computer.
Securing the System Partition
Secure System Partition command is only present on RISC-based computers, NOT Intel -based computers. You can use this command to secure RISC system partition (FAT: 2 MB). Once used, only members of the Administrators group on that computer are able to access the system partition. Security is not applied until the computer is restarted.
General Maintenance and Troubleshooting
Disk Configuration information is initially stored on the Emergency Repair Disk AND in the \Winnt_root\Repair folder After making changes such as reassigning drive letters, creating volume sets or stripe sets or creating new partitions, Disk Administrator provides an option for saving and later restoring this configuration information. Rdisk.exe in the system32 folder can be used to restore the configuration to its previous state in the last update operation. It lets you save the configuration information in a second place, off the hard drive. Restoring saved disk configuration is useful in these situations: Your computer was recently recovered with the Emergency Repair process and the registry was reset to its initial state. You may want to restore to the configuration before it was corrupted. You installed a new version of NT. File system corruption: You can reformat disk and restore from backup. Corrupted or lost files when you are running DOS: This is usually due to LFN. Failure to recognize hard disks or partitions: Detected hardware can be found in HKEY_LOCAL_MACHINE\HARDWARE Problem with 1 GB IDE disks: Due to a BIOS limit of 1024 cylinders (not an operating system limit), NT can not gain access to all of the space on the disk because the disk do not translate in a way that NT recognizes. To overcome this problem, either the BIOS must be able to circumvent the limit or NT must be able to communicate directly with the controller. NT can currently communicate only with WD 1003-compatible controllers. NT also supports OnTrack Systems Disk Manager, Atdisk.sys
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Last Updated: Wednesday, March 10, 1999 | Grant Wilson, Tisdale, SK. Canada