Module 6: Managing Partitions
There are two kinds of partitions:
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.
- 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.
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- 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.
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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.
- Use Disk Administrator to manage, partition, and format
hard disks. You can create stripe sets, volume sets and mirroring with it.
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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