Friday, March 14, 2014

Windows Server 2008 and beyond: NtfsDisableLastAccessUpdate disablesNTFS LastAccessTime by default

For Oracle database and other database engines implemented on UNIX or Linux systems, disabling atime access time updates to filesystems can be an important performance optimization.  For Oracle 11gr2 on AIX 7.1, using the noatime mount option for a JFS2 root filesystem should even be considered.
So when I learned about the NtfsDisableLastAccessUpdate registry setting, my first thought was: wow... why did it take so long for me to hear about this?
Now I know :-) I only started paying attention to the Windows Server world after WS2008. Turns out that for WS2008 and beyond, LastAccessTime updates are off by default, as cited below.

"<16> Section In Windows Vista/Windows Server 2008 and later, LastAccessTime updates are disabled by default in the ReFS and NTFS file systems. It is only updated when the file is closed. This behavior is controlled by the following registry key: HKLM\System\CurrentControlSet\Control\FileSystem\NtfsDisableLastAccessUpdate. A nonzero value means LastAccessTime updates are disabled. A value of zero means they are enabled."
****Updated 3/16/2014****
A registry query for filesystem options will indicate whether LastAccessTime is being maintained or not.  A value of 1 for NtfsDisableLastAccessUpdate means its not being maintained - this is default for Windows Server 2008 and beyond.  A value of 0 means this access time IS being maintained.
C:\Windows\system32>reg query HKLM\System\CurrentControlSet\Control\FileSystem\

    DisableDeleteNotification    REG_DWORD    0x0
    SymlinkLocalToLocalEvaluation    REG_DWORD    0x1
    SymlinkLocalToRemoteEvaluation    REG_DWORD    0x1
    SymlinkRemoteToLocalEvaluation    REG_DWORD    0x0
    SymlinkRemoteToRemoteEvaluation    REG_DWORD    0x0
    Win31FileSystem    REG_DWORD    0x0
    Win95TruncatedExtensions    REG_DWORD    0x1
    NtfsAllowExtendedCharacter8dot3Rename    REG_DWORD    0x0
    NtfsBugcheckOnCorrupt    REG_DWORD    0x0
    NtfsDisable8dot3NameCreation    REG_DWORD    0x2
    NtfsDisableCompression    REG_DWORD    0x0
    NtfsDisableEncryption    REG_DWORD    0x0
    NtfsDisableLastAccessUpdate    REG_DWORD    0x1
    NtfsDisableVolsnapHints    REG_DWORD    0x2
    NtfsEncryptPagingFile    REG_DWORD    0x0
    NtfsMemoryUsage    REG_DWORD    0x0
    NtfsMftZoneReservation    REG_DWORD    0x0
    NtfsQuotaNotifyRate    REG_DWORD    0xe10
    UdfsCloseSessionOnEject    REG_DWORD    0x3
    UdfsSoftwareDefectManagement    REG_DWORD    0x0

 ****End Updat****

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