Windows 7 and Optimization for Solid State Drives

Solid state drives are in our computing futures. While prices right now make them mostly impractical for those of us without unlimited cash cheat codes, prices will fall and we’ll be buying more of them instead of the standard magnetic, spinning hard disk drives.

Perhaps by the time that SSDs are affordable, we’ll still be using Windows 7 (which means within the next few years). Thankfully, Microsoft has included several features in Windows 7 that accounts for the presence of an SSD.

“Windows 7 tends to perform well on today’s SSDs, in part, because we made many engineering changes to reduce the frequency of writes and flushes. This benefits traditional HDDs as well, but is particularly helpful on today’s SSDs,” wrote Michael Fortin, one of Microsoft's Distinguished Engineers, in the Engineering Windows 7 blog.

When a solid state drive is present, Windows 7 will disable disk defragmentation, Superfetch, ReadyBoost, as well as boot and application launch prefetching.

“These technologies were all designed to improve performance on traditional HDDs, where random read performance could easily be a major bottleneck,” explained Fortin.  

One of the more notable advancements in Windows 7 is support for the Trim command. The reason for the command deals strictly with the way that data is written to NAND memory. For an exceptional explanation of why Trim is important, check out AnandTech’s article on the topic.

Fortin detailed how Trim will work in the upcoming OS:

“In Windows 7, if an SSD reports it supports the Trim attribute of the ATA protocol’s Data Set Management command, the NTFS file system will request the ATA driver to issue the new operation to the device when files are deleted and it is safe to erase the SSD pages backing the files. With this information, an SSD can plan to erase the relevant blocks opportunistically (and lazily) in the hope that subsequent writes will not require a blocking erase operation since erased pages are available for reuse.

“As an added benefit, the Trim operation can help SSDs reduce wear by eliminating the need for many merge operations to occur. As an example, consider a single 128 KB SSD block that contained a 128 KB file. If the file is deleted and a Trim operation is requested, then the SSD can avoid having to mix bytes from the SSD block with any other bytes that are subsequently written to that block. This reduces wear.

“Windows 7 requests the Trim operation for more than just file delete operations. The Trim operation is fully integrated with partition- and volume-level commands like Format and Delete, with file system commands relating to truncate and compression, and with the System Restore (aka Volume Snapshot) feature.”

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  • krazyderek
    So is this indeed a feature that is active now in RC 1 or win7? And if so, is it completely automatic and auto detected?
  • darkguset
    "When a solid state drive is present, Windows 7 will disable disk defragmentation, Superfetch, ReadyBoost, as well as boot and application launch prefetching."

    Does that mean that if you have a mix of HDDs and SSDs, those features will be completely disabled or just disabled on the SSD drives? It is not quite clear on that.
  • crisisavatar
    glad to hear this