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Start By Enabling AHCI (With TRIM)

Can You Get More Space Or Speed From Your SSD?
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Before we start implementing the various tweaks, we need to make sure our SATA controller is in AHCI mode and that the TRIM command is enabled in Windows 7.

You want AHCI turned on because it is the specification by which Native Command Queuing (a SATA-specific technology) is enabled. SSDs boast incredibly fast response times. So, they realize their best performance when fielding multiple commands simultaneously, consequently benefiting from the parallelism the defines most SSD architectures. This is precisely the reason we see better benchmark performance when we use queue depths of up to 32 versus a queue depth of one.

Verify the SATA controller is set to AHCI Mode:

  • During the installation process, you want to ensure your SATA controller is set to AHCI mode in the motherboard's BIOS or UEFI. AHCI is needed for native TRIM support in Windows 7, which helps maintain performance over time. 


Verify the SATA controller is set to AHCI Mode.

  • On the Start menu, select Control Panel.
  • Double-click 'System' from the Classic View (or the small or large icon view in Microsoft Windows 7).
  • Select 'Device Manager' in the left pane.
  • From the Device Manager, look for an entry named IDE ATA/ATAPI controllers.
  • If this entry is present, expand it and look for one of the controllers to list AHCI.
    • If an AHCI controller is identified, then the system is in AHCI mode.
    • If none of the controllers above are shown, then your system is not in AHCI mode.

  • If you already installed your operating system in legacy IDE mode, it is recommended to switch to AHCI after completing the steps listed in this Windows Article: http://support.microsoft.com/kb/922976, providing your platform supports AHCI.


Verify that TRIM is Enabled

Verifying TRIM will confirm that the TRIM commands are being sent from Windows to the SSD. How to Verify TRIM is enabled:

  • In the Start menu search box, type "cmd" without the quotes
  • Right-click the cmd program and select Run as Administrator
  • In the command line, type "fsutil behavior query DisableDeleteNotify", again without the quotes
    • if DisableDeleteNotify = 0, then TRIM is enabled
    • If DisableDeleteNotify = 1, then TRIM is disabled.


Per Wikipedia, TRIM is an ATA command that allows the operating system to tell an SSD what blocks of previously-saved data are no longer needed as a result of file deletions. This allows the SSD to handle garbage collection that would otherwise significantly slow down future write operations of the SSD.

With our test platform correctly configured, it's time to put these tweaks to the test.

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