Asus PIKE 2108 PIKE 2108 user's manual - Page 27
Always Write Back, Read Policy - bbu
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Here are brief explanations of the virtual drive options: • RAID Level: The drop-down menu lists the possible RAID levels for the virtual drive. Select RAID 1. • Strip Size: The strip size specifies the size of the segment written to each disk in a RAID configuration. You can set the strip size up to 64 KB. A larger strip size produces higher read performance. If your computer regularly performs random read requests, choose a smaller strip size. The default is 64 KB. • Access Policy: Select the type of data access that is allowed for this virtual drive: ◊ RW: Allow read/write access. This is the default. ◊ Read Only: Allow read-only access. ◊ Blocked: Do not allow access. • Read Policy: Specify the read policy for this virtual drive: ◊ Normal: This disables the read ahead capability. ◊ A head: This enables read ahead capability, which allows the controller to read sequentially ahead of requested data and to store the additional data in cache memory, anticipating that the data will be needed soon. This speeds up reads for sequential data, but there is little improvement when accessing random data. This is the default. • Write Policy: Specify the write policy for this virtual drive: ◊ W rite Through: In Write Through mode the controller sends a data transfer completion signal to the host when the drive subsystem has received all of the data in a transaction. ◊ A lways Write Back: In Writeback mode the controller sends a data transfer completion signal to the host when the controller cache has received all of the data in a transaction. This setting is recommended in Standard mode. ◊ W rite Back with BBU: In Writeback mode the controller sends a data transfer completion signal to the host when the controller cache has received all of the data in a transaction. This setting has to be used with a Battery Backup Unit (BBU). This is the default. • IO Policy: The IO Policy applies to reads on a specific virtual drive. It does not affect the read ahead cache. ◊ D irect: In direct I/O mode, reads are not buffered in cache memory. Data is transferred to the cache and the host concurrently. If the same data block is read again, it comes from cache memory. ◊ C ached: In cached I/O mode, all reads are buffered in cache memory. This is the default. • Drive Cache: Specify the drive cache policy: ASUS PIKE 2108 2-13