Auto-Rebuild. When you do not have a spare available, setting the Auto Rebuild policy allows rebuilds to occur with an available drive or with a failed drive. (For more information, see Setting the Auto-Rebuild Policy.)

Drive Performance Monitoring (DPM). DPM is an advanced trouble-shooting tool used to measure drive performance, and to help identify when a specific drive is causing problems so that you can repair or replace it. Commands are available through the 3ware CLI to enable and disable DPM, and to see a range of different statistics. These statistics can be useful to help troubleshoot problems with your RAID controller and units. For more information, see Drive Performance Monitoring.

Enclosure Services. Drives, fans, temperature sensors, and power supplies in supported chassis and enclosures can be identified by flashing LEDs so that you can quickly identify which component needs to be checked or replaced. For more information, see Enclosure Management.

Error Correction. Bad sectors can be dynamically repaired through error correction (Dynamic Sector Repair). Reallocation of blocks is based intelligently on the location of the block in relation to the stripe.

Scheduled Background Tasks. Initialize, rebuild, verify, and self-test tasks can all be run in the background, at scheduled times. This task lets you choose a time for these tasks to be run when it will be least disruptive to your system. You also can define the rate at which background tasks are performed, specifying whether I/O tasks should be given more processing time, or background rebuild and verify tasks should be given more processing time. (For more information, see Scheduling Background Tasks.)

SMART Monitoring. Self-Monitoring, Analysis and Reporting Technology (SMART) automatically checks the health of SATA and SAS disk drives every 24 hours and reports potential problems. This allows you to take proactive steps to prevent impending disk crashes. SMART data is checked on all disk drives (array members, single disks, and hot spares). Monitoring of SMART thresholds can be turned on and off in 3DM2. For more information, see Selecting Self-tests to be Performed and Viewing SMART Data About a Drive.

Staggered Spinup. Staggered spinup allows drives that support this feature to be powered-up into the standby power management state to minimize in-rush current at power-up and to allow the controller to sequence the spin-up of drives. Both SATA-2 OOB and ATA spin-up methods are supported. The standby power management state is persistent after power-down and power-up. You can set the number of drives that will spin up at the same time, and the time between staggers in 3BM and CLI. For more details, see Table: Default Settings for Policies/Background Tasks. This feature does not apply to drives that are attached to an expander. StorSave™ Profiles allow you to set the level of protection versus performance that is desired for a unit when write cache is enabled. (For more information, see Setting the StorSave Profile for a Unit.)

Verification and Media Scans. The verify task verifies all redundant units, and checks for media errors on single disks, spares and RAID 0 unit members. If the disk drive is part of a redundant unit, error locations that are found and are deemed repairable are rewritten with the redundant data. This forces the drive firmware to reallocate the error sectors accordingly. (For more information, see About Verification.)

Read Cache. Two read cache settings are available. Basic Read Cache stores data from media locally on the controller to improve read access times for applications. The 3ware Read Cache feature also includes an Intelligent Mode, which enables intelligent read prefetch (IRP). IRP includes a typical read-ahead caching method which is used to proactively retrieve data from media and store it locally on the controller with the anticipation that it may be requested by the host. By default read cache is set to the Intelligent mode. For more information, see Working with Read Cache Settings.

Write Cache. You can enable or disable write cache using 3BM, 3DM2, and CLI. When write cache is enabled, data will be stored in 3ware controller cache and drive cache before the data is committed to disk. This allows the system to process multiple write commands at the same time, thus improving performance. However when data is stored in cache, it could be lost if a power failure occurs. With a battery backup unit (BBU) installed, the data stored on the 3ware controller can be restored. (For more information, see Enabling and Disabling the Unit Write Cache.