Smart Array Controller Technology: Drive Array Expansion and Extension
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volume extension
in Windows
Operating systems within the Windows family support online drive extension
under specific conditions. To understand these conditions, an administrator
must first recognize the differences between Windows basic and dynamic
disks.
A basic disk uses Microsoft’s classic partition system in which each volume uses
only one partition. This system is the default in Windows NT, Windows 9x, and
DOS. An administrator can perform volume extensions using ACU or ACU-XE if
the system uses basic disks. The administrator can use the new space on the
logical drive for an additional partition, or can grow the existing partition by
using a third-party software utility such as PowerQuest’s Partition Magic.
Windows 2000 supports basic and dynamic disks, with dynamic disks being the
default partition system. A Windows 2000 dynamic disk is a physical disk that
doesn’t use static partitions or logical drives. Instead, it contains only dynamic
volumes that can span multiple partitions. Dynamic disks are created in the
Disk Management console of Windows 2000 and contain database tables at
the beginning and the end of the dynamic volume to recognize the partition
boundaries. Because this database may still exist even after a logical drive is
deleted, an administrator must be careful when performing volume extension
on a dynamic drive.
The best way to grow a volume size in Windows 2000 is to take advantage of
this dynamic disk functionality, rather than performing a volume extension in
ACU or ACU-XE. Because a dynamic disk can span multiple partitions on
separate logical drives, an administrator can create a completely new logical
drive when free space exists. Then the administrator can create a new
partition on the logical drive and add it as a segment to the existing volume
(this is what Microsoft calls expansion
4
). This functionally is the same as
extending the volume size in ACU or ACU-XE.
If an administrator desires to use ACU or ACU-XE to extend a volume, the
administrator should determine whether the drives are pristine – that is, the
physical drives have never been used for any other dynamic disk. If so, the
administrator should download and apply the Microsoft Service Pack 3. This
ensures proper compatibility between Microsoft dynamic disks and logical
volume extension using Smart Array Controllers.
If the administrator is trying to extend a volume of dynamic disks on previously
used physical drives, the database used for a dynamic disk may still exist even
after the logical drive is deleted. In this case, when an administrator performs
volume extension, the OS may see this old database. In this case, the partition
on the logical drive may be marked as a foreign disk and become unusable.
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Microsoft expansion refers to adding partitions to a volume using dynamic disks and growing the size of that volume.
