Dell PowerVault MD3220i Owner's Manual - Page 56
Monitoring MD3200i Series System Performance, virtual disk.
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paths to the RAID controller module that owns the virtual disk equally for I/O activity. Paths to the secondary RAID controller module are ignored until ownership changes. The basic assumption for the round-robin policy is that the data paths are equal. With mixed host support, the data paths might have different bandwidths or different data transfer speeds. • Least queue depth with subset-The least queue depth with subset policy is also known as the least I/Os or least requests policy. This policy routes the next I/O request to a data path that has the least outstanding I/O requests queued. For this policy, an I/O request is simply a command in the queue. The type of command or the number of blocks that are associated with the command are not considered.The least queue depth with subset policy treats large block requests and small block requests equally. The data path selected is one of the paths in the path group of the RAID controller module that owns the virtual disk. • Least path weight with subset (Windows operating systems only)-The least queue depth with subset policy is also known as the least I/Os or least requests policy. This policy routes the next I/O request to a data path that has the least outstanding I/O requests queued. For this policy, an I/O request is simply a command in the queue. The type of command or the number of blocks that are associated with the command are not considered. The least queue depth with subset policy treats large block requests and small block requests equally. The data path selected is one of the paths in the path group of the RAID controller module that owns the virtual disk. Monitoring MD3200i Series System Performance You can use the Performance Monitor to select virtual disks and RAID controller modules to monitor or to change the polling interval. Keep these guidelines in mind when using the Performance Monitor: • The Performance Monitor does not dynamically update its display if any configuration changes occur while the window is open. You must close the Performance Monitor window and reopen it for the changes to appear. • Using the Performance Monitor to retrieve performance data can affect the normal storage array performance depending on the polling interval that you set. 56 Planning: MD3200i Series Storage Array Terms and Concepts