The disk space requirements for a migration are dependent on the size of the migration store and the type of migration. You can estimate the amount of disk space needed for computers in your organization based on information about your organization's infrastructure. You can also calculate the disk space requirements using the ScanState tool.
In This Topic
- Hard Disk Space
Requirements. Describes the disk space requirements for the
migration store and other considerations on the source and
destination computers.
- Calculate Disk
Space Requirements Using the ScanState Tool. Describes how to
use the ScanState tool to determine how big the migration store
will be on a particular computer.
- Estimate
Migration Store Size. Describes how to estimate the average
size of migration stores for the computers in your organization,
based on your infrastructure.
Hard Disk Space Requirements
- Store. For non-hard-link migrations,
you should ensure that there is enough available disk space at the
location where you will save your store to contain the data being
migrated. You can save your store to another partition, an external
storage device such as a USB flash drive or a server. For more
information, see Choose a Migration Store
Type.
- Source computer. The source computer
needs enough available space for the following:
- 250 megabytes (MB) minimum of hard
disk space. Space is needed to support USMT operations, for
example, growth in the page file. Provided that every volume
involved in the migration is formatted as NTFS, 250 MB should
be enough space to ensure success for almost every hard-link
migration, regardless of the size of the migration. The USMT tools
will not create the migration store if 250 MB of disk space is
not available.
- Temporary space for USMT to run.
Additional disk space for the USMT tools to operate is required.
This does not include the minimum 250 MB needed to create the
migration store. The amount of temporary space required can be
calculated using the ScanState tool.
- Hard-link migration store. It is not
necessary to estimate the size of a hard-link migration store. The
only case where the hard-link store can be quite large is when
non-NTFS file systems exist on the system and contain data being
migrated. Since NTFS has been the default file system format for
Windows® XP and Windows Vista®, this situation is
unusual.
- 250 megabytes (MB) minimum of hard
disk space. Space is needed to support USMT operations, for
example, growth in the page file. Provided that every volume
involved in the migration is formatted as NTFS, 250 MB should
be enough space to ensure success for almost every hard-link
migration, regardless of the size of the migration. The USMT tools
will not create the migration store if 250 MB of disk space is
not available.
- Destination computer. The destination
computer needs enough available space for the following:
- Operating system.
- Applications.
- Data being migrated. It is important
to consider that in addition to the files being migrated, registry
information will also require hard disk space for storage.
- Temporary space for USMT to run.
Additional disk space for the USMT tools to operate is required.
The amount of temporary space required can be calculated using the
ScanState tool.
- Operating system.
Calculate Disk Space Requirements using the ScanState Tool
You can use the ScanState tool to calculate the disk space requirements for a particular compressed or uncompressed migration. It is not necessary to estimate the migration store size for a hard-link migration since this method does not create a separate migration store. The ScanState tool provides disk space requirements for the state of the computer at the time the tool is run. The state of the computer may change during day to day use so it is recommended that you use the calculations as an estimate when planning your migration.
To run the ScanState tool on the source computer with USMT installed,
- Open a command prompt with administrator privileges. For
example, in Windows Vista, click Start, click All
Programs, click Accessories, right-click Command
Prompt, and select Run as administrator.
- Navigate to the USMT tools. For example, type
cd /d "c:\program files\Windows AIK\Tools\USMT\<architecture>"
- Run the ScanState tool to generate an XML report of the space
requirements. At the command prompt, type
ScanState.exe <StorePath> /p:<path to a file>
ScanState.exe c:\store /p:c:\spaceRequirements.xml
StorePath
is a required parameter.
The ScanState tool also allows you to estimate disk space requirements based on a customized migration. For example, you might not want to migrate the My Documents folder to the destination computer. You can specify this in a configuration file when you run the ScanState tool. For more information, see Customize USMT XML Files.
Note | |
To preserve the functionality of existing applications or scripts that require the previous behavior of USMT, the /p option, without specifying <path to a file> is still available in USMT 4.0. If you specify only the /p option, the storage space estimations will be created based on USMT 3.x criteria. |
The space requirements report provides two elements, <storeSize> and <temporarySpace>. The <temporarySpace> value shows the disk space, in bytes, that USMT uses to operate during the migration—this does not include the minimum 250 MB needed to support USMT. The <storeSize> value shows the disk space, in bytes, required to host the migration store contents on both the source and destination computers. The following example shows a report generated using /p:<path to a file>.
<?xml version="1.0" encoding="UTF-8"?> <PreMigration> <storeSize> <size clusterSize="4096">11010592768</size> </storeSize> <temporarySpace> <size>58189144</size> </temporarySpace> </PreMigration>
Additionally, USMT performs a compliance check for a required minimum of 250 MB of available disk space and will not create a store if the compliance check fails.
Estimate Migration Store Size
Determine how much space you will need to store the migrated data. You should base your calculations on the volume of e-mail, personal documents, and system settings for each user. The best way to estimate these is to survey several computers to arrive at an average for the size of the store that you will need.
The amount of space that is required in the store will vary, depending on the local storage strategies your organization uses. For example, one key element that determines the size of migration data sets is e-mail storage. If e-mail is stored centrally, data sets will be smaller. If e-mail is stored locally, such as offline-storage files, data sets will be larger. Mobile users will typically have larger data sets than workstation users. You should perform tests and inventory the network to determine the average data set size in your organization.
Note | |
You can create a space-estimate file (Usmtsize.txt), by using the legacy /p command-line option to estimate the size of the store. |
When trying to determine how much disk space you will need, consider the following issues:
- E-mail: If users deal with a large
volume of e-mail or keep e-mail on their local computers instead of
on a mail server, the e-mail can take up as much disk space as all
other user files combined. Prior to migrating user data, make sure
that users who store e-mail locally synchronize their inboxes with
their mail server.
- User documents: Frequently, all of a
user's documents fit into 50 MB of space, depending on the
types of files involved. This estimate assumes typical office work,
such as word-processing documents and spreadsheets. This estimate
can vary substantially based on the types of documents that your
organization uses. For example, an architectural firm that
predominantly uses computer-aided design (CAD) files needs much
more space than a law firm that primarily uses word-processing
documents. You do not need to migrate the documents that users
store on file servers through mechanisms such as Folder
Redirection, as long as users will have access to these locations
after the migration.
- User system settings: Five megabytes
is usually adequate space to save the registry settings. This
requirement can fluctuate, however, based on the number of
applications that have been installed. It is rare, however, for the
user-specific portion of the registry to exceed 5 MB.