3Ware 7506-8 User Guide - Page 112

Troubleshooting: Problems and Solutions AEN 02Eh AEN_REPLACE_DRIVE_TOO_SMALL The ATA RAID controller notifies the user by this AEN when the replacement drive capacity is smaller than required. The replacement drive must be equal to or greater capacity than the drive it's replacing. For more information refer to the Hint on page 32. AEN 02Fh AEN_UNIT_NOT_ZEROED The ATA RAID controller notifies the user by this AEN when verification fails because the array has not been initialized. This is normal for the first verification that occurs on a RAID 1 or RAID 10 array. AEN 021h AEN_UDMA_DOWNGRADE The ATA RAID controller communicates to the ATA disk drives through the Ultra DMA (UDMA) protocol. This protocol ensures data integrity across the ATA cable by appending a Cyclical Redundancy Check (CRC) for all ATA data that is transferred. If the data becomes corrupted between the drive and the ATA RAID controller (e.g., an intermittent cable connection) the ATA RAID controller detects this as a UDMA CRC or cable error. The ATA RAID controller then retries the failed command three times at the current UDMA transfer rate. If the error persists, it lowers the UDMA transfer rate (e.g., from UDMA 100 to UDMA 66) and retries another three times. This AEN is sent to the user when the ATA RAID controller lowers the UDMA transfer rate. Possible causes of UDMA CRC errors are intermittent or bad ATA interface cables or cable routing problems through electrically noisy environments (e.g., cables are too close to the power supply). AEN 023h AEN_SECTOR_REPAIR The ATA RAID controller supports a feature called dynamic sector repair to allow the unit to recover from certain drive errors that would normally result in a degraded array situation. For redundant arrays such as RAID 1, 10 and 5, the ATA RAID controller essentially has two copies of the users data available. If a read command to a sector on a disk drive results in an error, it reverts to the redundant copy in order to satisfy the host's request. At this point, the ATA RAID controller has a good copy of the requested data in its cache memory. It will then use this data to force the failing drive to reallocate the bad sector, which essentially repairs the sector. When a sector repair occurs, the user is notified by this AEN. The fact that a sector repair AEN has been sent to the user is an indication of the presence of grown defects on a particular drive. While typical modern disk drives are designed to allow several hundred grown defects, special attention should be paid to any drive in an array that begins to indicate sector repair messages. This may be an indication of a drive that is beginning to fail. The user may wish to replace the drive, especially if the number of sector repair errors exceeds 3 per month. 104 3ware Escalade ATA RAID Controller User Guide