3Ware 3W-7410 - Escalade 7410 RAID Controller, Manual

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Troubleshooting: Problems and Solutions
104 3ware Escalade ATA RAID Controller User Guide
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 ver-
ification 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 avail-
able. 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 mem-
ory. It will then use this data to force the failing drive to reallocate the bad sec-
tor, 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.