This article describes file and folder compression performance in Windows when the NTFS File System is being used.
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While NTFS file system compression can save disk space,
compressing data can adversely affect performance. NTFS compression has the
following performance characteristics. When you copy or move a compressed NTFS
file to a different folder, NTFS decompresses the file, copies or moves the
file to the new location, and then recompresses the file. This behavior occurs
even when the file is copied or moved between folders on the same computer.
Compressed files are also expanded before copying over the network, so NTFS
compression does not save network bandwidth.
Because NTFS compression
is processor-intensive, the performance cost is more noticeable on servers,
which are frequently processor-bound. Heavily loaded servers with a lot of
write traffic are poor candidates for data compression. However, you may not
experience significant performance degradation with read-only, read-mostly, or
lightly loaded servers.
If you run a program that uses transaction
logging and that constantly writes to a database or log, configure the program
to store its files on a volume that is not compressed. If a program modifies
data through mapped sections in a compressed file, the program can produce
"dirty" pages faster than the mapped writer can write them. Programs such as
Microsoft Message Queuing (also known as MSMQ) do not work with NTFS
compression because of this issue.
Because user home folders and roaming profiles use lots of read and write operations, Microsoft
recommends that you put user home folders and roaming profiles on a volume that
does not have NTFS compression on the parent folder or on the volume root. Individual users may still enable compression on their folders, but the overall number of compressed files and folders is smaller. On servers that host compressed volumes, you should use careful performance monitoring to determine whether the CPU has enough capacity to support the compress/decompress operations that are being performed.
For additional information, see the
"File and Folder Compression" and "Compression Performance" sections in the
Microsoft Windows 2000 Resource Kit.
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