Determine Where to Store Data

Consider these questions when deciding where to store data during migration:

  • How much space do I need for the store?
  • How much space do I need on the destination computer?
  • Should I store the data remotely or locally?

How much space do I need for the store?

You first need to 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 average desktops to estimate the size the store that you will need.

The amount of space that is required in the store will vary depending on the local storage strategies each 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, as in offline storage files, data sets will be larger. Mobile users especially 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.


You can create a space-estimate file (Usmtsize.txt) using the /p 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 megabytes (MB) of space, depending on the types of files they work with. This estimate assumes typical office work such as word processing documents and spreadsheets. This estimate can fluctuate 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 like Folder Redirection, as long as they will have access to these locations after the migration.
  • User system settings: 5 MB is usually adequate to save the registry settings. This requirement can fluctuate based on the number of applications that have been installed, but it is rare for the user-specific portion of the registry to exceed 5 MB.

The following table provides storage space estimates for each user's profile and e-mail. The estimates do not account for any files that are migrated from the source computer. These estimates are based on the above factors and a hypothetical office situation. You should check these estimates against your own environment as intermediate stores can greatly vary depending on the type and size of the collected files. You should allow a minimum buffer of 20 percent additional space on the intermediate store.

User Type Intermediate Store Estimate

Desktop user storing e-mail on server

50 MB to 75 MB (plus any collected files)

Desktop user with local e-mail storage

150 MB to 200 MB (plus any collected files)

Laptop user

150 MB to 300+ MB (plus any collected files)

How much space do I need on the destination computer?

The destination computer will need enough available space for the following:

  • Operating system
  • Applications
  • Size of the uncompressed store*
  • Twice the size of the largest file that will be migrated*


You will need the last two items listed because when you run LoadState on the destination computer, LoadState migrates each file (one by one) from the store to a temporary location on the destination computer. The files are decompressed (and decrypted if necessary) during this process. Then LoadState transfers the file to the correct location, deletes the temporary copy, and begins migrating the next file.

Should I store the data remotely or locally?

If you have enough space and you are migrating the user state back to the same computer, then storing data on a local device is normally the best option to reduce server storage costs and network performance issues. You can store the data locally either on a different partition or on removable device such as a Universal Serial Bus (USB) drive. Also, depending on the imaging technology that you are using, you might be able to store the data on the partition that is being re-imaged (if the data will be protected from deletion during the process). To increase performance, you should store the data on high-speed drives that use a high-speed network connection. It is also good practice to ensure that the migration is the only task the server is performing.

If there is not enough local disk space, or if you are moving the user state to a new computer, then you must store the data remotely. For example, you can store it in on a shared folder, on media that you can remove (such as a USB drive), or you can store it directly on the destination computer. For example, create and share C:\store on the destination computer. Then run ScanState on the source computer and save the files and settings to \\DestinationComputerName\store. Then, run LoadState on the destination computer and specify C:\store as the store location. By doing this, you do not need to save the files to a server.


If possible, you should have users to store their data within their %UserProfile%\My Documents and %UserProfile%\Application Data folders. This will reduce the chance of USMT missing critical user data that is located in a directory that USMT is not configured to check.