Managing DrivesThe Drive Management feature provides settings for managing storage and lets you apply global settingsfor drives on your px2-300d Network Storage. The Drive Management feature also enables you to add andmanage Storage Pools on your px2-300d.Write CachingWrite Caching is a global setting that applies to all drives in your px2-300d. To set the disk write cachingvalue, click the Settings icon and select an option from the drop-down menu. The settings options areAlways disabled, Enabled with UPS, or Always enabled.Enabling Disk Write Caching is not the same as creating an SSD Cache. See ImprovingPerformance with a Cache Pool for information on how to create and use an SSD Cache.Understanding Disk Write CachingWrite caching is a mechanism that attempts to separate the fast processing speed of the px2-300d fromthe relatively slow mechanics of actually writing data to drive.When write caching is disabled, every write to drive causes the px2-300d to wait while the data is writtento drive, which can slow performance. When write caching is enabled and the px2-300d sends a writerequest to the drive, it writes the data to cache (which is much faster) and sends an immediateacknowledgment to the px2-300d saying the write is complete. The system proceeds without waiting forthe data to actually get written to drive, which occurs in the background.While write caching does improve performance, there are some risks. The system responds that the datais written to drive when in fact it has only been written to cache. Should the px2-300d lose power, any datanot completely written to drive is lost forever.This is because cache memory is volatile. If you lose power, the contents of the cache are lost. Therefore,if there were any pending writes in the cache that were not written to the drive, they will be lost forever.Using a UPS (Uninterrupted Power Supply) can mitigate the risk associated with write caching, which iswhy it is recommended to only enable this feature when a UPS is connected.Global Drive Management Settings1. Click Settings to access the global drive management settings available on your px2-300d.2. Select the link Perform an offline file system check then reboot if any of the followingconditions exist on your px2-300d:○ Data is unavailable○ Data is missing after an unclean shutdown○ You are concerned about the integrity of the file systemThis option will take the volume offline for some time. The check could take up to several hours,depending on the size of the volume and other factors. During the check, data will beinaccessible. When the check is completed, it will reboot the device.3. Select a value for Disk Write Caching. See Understanding Disk Write Caching for moreinformation on the options.4. Click Apply to save your changes.Drive Management71 Managing Drives
