ID Number: Q46086
1.00 1.10 1.11 4.20
OS/2
Summary:
The following information discusses how hard disks should be
partitioned to allow for optimal performance of database devices in
SQL Server.
More Information:
SQL Server acquires disk space from OS/2 when DISK INIT is executed by
allocating a normal OS/2 file-system file of the specified size. The
smallest increment is 1 megabyte (MB); this is true regardless of the
size of the disk partition or file-system cluster size. SQL Server
keeps track of how that space is used by the various tables and
database objects through "allocation pages," which occur every 256th
page. This scheme could allow DISK INIT to allocate an OS/2 file as
small as 1/2 MB (256 2K pages); however, the smallest increment is 1
MB.
The allocation pages are used by SQL Server to keep track of how the
disk space is being used by the various tables and database objects
within SQL Server. As far as OS/2 and the file system are concerned,
the space was allocated when the DISK INIT was executed and never
changes.
There is no advantage to partitioning the hard disk so that it results
in smaller cluster sizes because the space is statically allocated and
never changes. The only performance concern is to minimize disk-head
movement. Database devices should either be allocated on a newly
formatted disk or compacted with a disk-organizer utility to be sure
that all of the clusters of the database devices are physically
contiguous on the disk. If multiple physical drives are available, the
most heavily used data should be allocated on different database
devices, which should in turn be placed on different physical drives.
Putting different database devices on different logical drives does
not improve performance.
Additional reference words: 1.00 1.10 1.11 4.20