Windows Server 2003 disk storage sizing

The installation of Windows Server 2003 on an IXA server or IXS creates two network server storage spaces representing the server’s C: and D: drives. The C: drive contains the Windows Server 2003 system files. The D: drive holds an image of the Windows Server 2003

installation source files, plus other files supplied by IBM as part of the Integration for Windows Server (5722-WSV) program product. It is important that you accurately estimate the amount of disk storage needed for these two storage spaces before you begin the installation.

If you are not already familiar with the basic concepts behind iSeries and Windows Server 2003 disk management, refer to 5.2, “Managing Network Server Storage Spaces on the iSeries” on page 114.

2.7.1 Windows Server 2003 C: and D: drive sizes

Take these considerations into account when estimating the size of the C: and D: drives on your Windows Server 2003:

The more memory you have installed on the integrated server hardware, the larger you should make the C: drive. Refer to “Windows Server 2003 virtual memory paging file” on page 38 for more information about how the amount of memory installed on the Windows server affects the size of the C: drive.

When applications are installed on the server, many of them install some of their files on the system (C:) drive, so allow for this requirement.

When you install a Windows Server 2003 service pack, you have the option of saving the files that are replaced, in case you need to uninstall the service pack. If you choose to take advantage of the uninstall option, you may require up to 100 MB of additional free space on the system drive.

Future versions of Windows Server 2003 may require additional free space on the C: drive to allow for an upgrade of the existing installation.

The D: drive only needs to be large enough to accommodate the Windows Server 2003 installation source files, client-side integration software, and any future updates to the integration software (provided by service packs).

For an IXA or IXS, the C: drive can be from 500 MB to 64000 MB in size. If the C: drive is larger than 2047 MB, it may automatically convert to NTFS, depending on a number of factors, such as:

– INS hardware: The 200Mhz and 333Mhz models do not support FAT32, thus the C:

drive will always convert to NTFS when the size is greater than 2047MB, to a maximum of 8000 MB).

– Windows NT 4.0 will always automatically convert to NTFS when more than 2047 MB.

– IXS support for Extended INT-13 BIOS support allows for FAT32 drives up to 32000 MB for Windows 2000 and Windows Server 2003.

– Larger than the Windows server FAT32 limit of 32 GB will always convert to NTFS.

The minimum requirement for a Windows Server 2003 system drive is 1.5 GB.

The D: drive can be up to 2047 MB in size and must remain formatted as FAT. The

INSWNTSVR command increases the size of your D: drive to 762 MB if you enter anything less than that.

As long as you stay below 64000 MB disk sizes, you can expand the partitions if your needs change. See 5.2.3, “Expanding storage on integrated Windows servers” on page 123, and 5.2.4, “Expanding the Windows system partition” on page 126. However, it is strongly recommended that you allocate plenty of space to the C: drive as it is difficult to enlarge after it has been created.

Instead of specifying a size for the C: and D: drives when running the Install Windows Server command (INSWNTSVR), you can specify the *CALC option. This estimates the size of the C: and D: drives as follows:

C: drive

*CALC specifies that the size should be calculated based on the installed memory of the xSeries server. It calculates a size that is double the amount of installed memory plus the minimum size specified in the TXTSETUP.SIF file, FreeSysPartDiskSpace parameter. The TXTSETUP.SIF file is located in the Windows install source image either on CD-ROM or in the integrated file system, as specified by the Windows source directory (WNTSRCDIR) parameter of the INSWNTSVR command.

D: drive

*CALC specifies that the size should be calculated based on the space required to hold the install source image located on CD-ROM or in the IFS as specified by the Windows source directory (WNTSRCDIR) parameter.

You can use *CALC to estimate the size of the D: drive, but it is recommended you that manually calculate your C: drive requirements using the information in this section.

2.7.2 Windows Server 2003 virtual memory paging file

Windows Server 2003 creates a virtual memory paging file (pagefile.sys) on the system drive.

This file is used to handle the swapping of data in and out of memory, as well as being used as a temporary dump file for STOP (blue screen) errors.

Windows Server 2003 calculates the size of the paging file based on the amount of physical memory (RAM) installed on the server. It is generally recommended that you allow at least 150% of the installed memory size as additional disk storage on the system drive to accommodate the paging file. For example, on an IXA server with 512 MB of RAM, you should allow for a paging file size of 768 MB when considering how large to make the system drive. The more memory that is installed on your IXA server or IXS, the greater the amount of disk space you should reserve on your C: drive for the paging file.

2.7.3 User file storage

User files should be stored on drives other than C: and D:. After installation you can create additional Windows Server 2003 drives to hold user files. You should do this because the growth of data files might overflow a drive’s capacity, and it may be difficult to enlarge the system (C:) drive. Also, it is good practice to store system files, application files, and user data on different drives for backup and data migration purposes.

Windows Server 2003 sees a network server storage space as a physical disk drive that you would install in a PC server. Network server storage spaces can be from 1 MB to 64000 MB in size, depending on which file system format you choose at the time of creation. See Table 5-1, “Windows file systems and sizes” on page 116, for a comparison of the various Windows Server 2003 file systems.

Because iSeries disk data management automatically scatters data over all disk drives in the ASP, you do not need to worry about how many disk arms are accessing your Windows data.

By default, every network server storage space is striped across all disk drives in the ASP.

Therefore, the integrated Windows server always uses the maximum number of disk arms to access data. As a consequence, you can make your network server storage spaces as large as you want without worrying about adversely affecting performance. However, you should avoid creating a network server storage space that far exceeds your short- to mid-term storage capacity needs: It wastes disk storage that could otherwise be used by the iSeries,

and could have negative implications for your Windows backup strategy if you are going to back up your storage spaces as objects on the iSeries. For more information about backing up an integrated Windows server, refer to Chapter 7, “Backup and recovery” on page 179.

2.7.4 User auxiliary storage pools

When you install Windows Server 2003 on the IXA or IXS, you can choose to create the C:

and D: drive storage spaces in the system auxiliary storage pool (ASP) or a user ASP, which can also be an Independent Auxiliary Storage Pool (IASP). You have the same flexibility when creating additional network server storage spaces for Windows Server 2003.

Locating network server storage spaces in user ASPs could improve overall system performance because you may be able to move user data to lightly used disk units or move infrequently used data to slow disks.

User ASPs should only be set up on larger systems with enough disk arms to maintain good performance by someone who is familiar with this technology. It is recommended that you do not use user ASPs unless you have fully investigated their applicability to your environment.

2.7.5 Disk storage recommendations

These minimum sizes for Windows Server 2003 C: and D: drives are recommended:

C: drive: 1500 MB + (1.5 x installed memory)

It is recommended that you allocate at least 2048 MB to the C: drive.

The Windows Server 2003 operating system requires approximately 1.2 GB, so the recommended figure allows some additional disk storage for application files, which may need to reside on the system drive. You may want to make the C: drive considerably larger than the minimum recommended size to allow for the installation of additional memory, Active Directory, DNS, DHCP, and other applications.

D: drive: 762 MB

Because the files that are stored on the D: drive are static in nature, you do not need to allow a large amount of free space.