Should the TEMP dir be on a separate drive?

Question

I have a new physical drive, with room to spare. I have allocated a spare partition on this drive. Should I have my Windows TMP/TEMP env-var pointing to this partition?

1. On the one hand, it would seem beneficial having ANY files (your system is currently dealing with), on a different drive, alleviating some of the contention.
   With this approach in mind, it is basically beneficial having every disjoint set of files on a different physical drive, were it possible.
2. On the other hand, I can imagine the following common practice.
   Installer unpacks/compiles a bunch of files to the userTemp dir' (currently located under the C drive). Once the unpacking is done, all files are copied to the "C:\Program Files" dir'
   Under this scenario, having TEMP on a different partition would mean actually transferring all the data from one partition to the other. If the TEMP dir' was on the system partition, the above just boils down to a quick re-pointing of the file-system.

Has anyone tried/compared both scenarios?

Answer 1

Benefits of moving TEMP and TMP to a different drive will be significant in cases where those directories are heavily used, such as an Exchange server. http://technet.microsoft.com/en-us/library/aa998306(v=exchg.80).aspx states:

As a best practice, it is recommended that the TEMP and TMP folders be stored on a disk subsystem that is not shared by your system folder or the Exchange data files. The Microsoft Exchange Information Store service uses the TEMP and TMP folders as temporary storage during various operations, such as message conversion, working with large attachments, and mailbox move operations...TEMP is typically used by applications, such as Microsoft Exchange, and TMP is typically used by development tools, such as Microsoft Visual C++

On a Windows 7 desktop, performance degradation was noticed when TEMP was on a different drive - just like you mentioned in point #2 - when extracting large compressed tarballs and zip files. I have noticed performance improvement moving the pagefile to a different drive. Technet article on Learn Best Practices for Optimizing the Virtual Memory Configuration (http://technet.microsoft.com/en-us/magazine/ff382717.aspx) mentions:

If you have more than one physical disk, moving the page file to a fast drive that doesn't contain your Windows system files is a good idea.

On Windows 7 desktops and laptops with 8 to 16 GB memory and an SSD, TEMP/TMP and pagefile are on the same drive. I have no complains about performance. Based on my experiences I recommend using SSD and keeping TEMP/TMP/pagefile on the same drive. On traditional HDDs, moving pagefile to a different drive on a busy system might help more than moving TEMP/TMP directories. Whether to move TEMP/TMP/pagefile to a different drive will depend on how the system is used.