Rick has years of IT experience and focuses on virtualization, Windows-based server administration, and system hardware. Let's start with the format task for a new drive on a Windows Server, which is the point where administrators can make a decision about allocation unit size. Figure A shows the allocation unit menu. Windows is adaptive in the size of the volume and displaying the available allocation unit sizes for a volume based on its size.
Consider this example with a single drive that was initially 13 TB and then expanded to 19 TB. Once the drive passed to being larger than 16 TB, the 8K allocation unit is the smallest option Figure B. Figure B The allocation unit is very important, as it represents the smallest unit of consumption on disk. For example, if you have a small text file that is 1, bytes, it will consume a full allocation unit of 8K on disk.
Larger files that span multiple allocation units will have the remainder available, but smaller files can quickly consume disk space on large volumes; this is the difference between the Size and the Size On Disk display options in Windows Explorer. This example is shown in Figure C. To do so, follow these steps:.
Click Start , click Run , type cmd , and then click OK. Multiply each value that the output reports in kilobytes KB by to determine accurate byte counts. You can use this information to determine how your disk space is being used and the default cluster size.
To determine whether this is the optimal cluster size, you must determine the wasted space on your disk. Click Start , click My Computer , and then double-click the drive letter for example, D of the volume in question to open the volume and display the folders and files that the root contains.
Click any file or folder, and then click Select All on the Edit menu. With all the files and folders selected, right-click any file or folder, click Properties , and then click the General tab. You can only change the cluster size you are using by reformatting the volume. Alternately, you can enable NTFS compression to regain space that you lost because of an incorrect cluster size. However, this may result in decreased performance.
By default, Files hidden files and protected operating system files are excluded. This behavior may cause Windows Explorer or the dir command to display inaccurate file and folder totals and size statistics.
To include these types of files in the overall statistics, change Folder Options. In the Backup Utility, click the Backup tab, and then select the check box for the whole volume that is affected for example: D: , and then click Start Backup. After the backup is complete, open the backup report and compare folder for folder the NTBackup log output with the d-dir.
Because backup can access all the files, its report may contain folders and files that Windows Explorer and the dir command do not display. You may find it easier to use the NTBackup interface to locate the volume without backing up the volume when you want to search for large files or folders that you cannot access by using Windows Explorer. After you locate the files that you do not have access to, you can add or change permissions by using the Security tab while you view the properties of the file or folder in Windows Explorer.
By default, you cannot access the System Volume Information folder. You may notice folders or files that do not have a Security tab. Or, you may not be able to re-assign permissions to the affected folders and files. You may receive the following error message when you try to access them:.
If you have any such folders, contact Microsoft Product Support Services for additional help. Folders or files that contain invalid or reserved file names may also be excluded from file and folder statistics. Folders or files that contain leading or trailing spaces are valid in NTFS, but they are not valid from a Win32 subsystem point of view. Connect and share knowledge within a single location that is structured and easy to search. When an application accesses files stored in random folders it takes ms to read each file.
With a test tool it seems that the delay occurs when opening the file. Reading the data then only takes a fraction of the time. In summary this means that reading 50 files can easily take seconds which is much more than expected. Writing is done in batch so performance is not an issue here.
As mentioned in the comments the system runs Symantec Endpoint Protection. However, disabling it does not change the read times. PerfMon measures ms per read. The server did not have enough memory. Instead of caching NTFS metafile data in memory every file access required multiple disk reads.
As usual, the issue is obvious once you see it. Let me share what clouded my perspective:. So either Windows decided that the available memory was not enough to hold a meaningful part of the metafile data. Or some internal restriction does not allow to use the last bit of memory for metafile data. However, RamMap reported multiple GB of metafile data being held as standby data. Apparently, the standby data can have a substantial impact. Sign up to join this community.
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