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Device I/O Parameters

Device I/O Dialog Box   Device I/O Handler Script


A way to access disk/volume (may be set when selecting device).

OS Windows

IO FILEuse ReadFile/WriteFile functions to access device
IO SCSIuse SCSI driver (lower level, recommended to reduce the number of OS I/O attempts, to bypass OS write blocking)
IO ATAuse ATA driver
Overlappeduse overlapped I/O (does not affect I/O, not recommended)


I/O Errors

A way to handle I/O errors.

Skip I/O Errors: an option to automatically continue an operation after a number of auto retries when I/O errors happen. If turned off the user choice is required within I/O dialog box.

Do not wait if device is not ready: continue an operation even if a device is not ready (not recommended).

always: apply to future operations.
now: apply to current operation.

Auto retries number on CRC Error: a number of additional I/O retries when an I/O error happens. Do not use IO FILE interface to avoid OS Windows additional retries and delays.

Zero value (0) stands for no additional retries, herewith the rest sectors of the block after the error will not be read to the I/O buffer.

If the value is non-zero then sectors are being read one by one until an I/O error is encountered. The error sector is being read until the number of auto retries is reached or the sector is read succesfully.

Increasing of retries number increases the percent of data successfully read but decreases device lifetime due to heavy load.

Auto retries number on Seek Error: additional I/O retries for errors other than "CRC".

Input error is assumed to be a seek error if I/O buffer contents is not changed after I/O (or it is zero filled). Usually seek errors significantly slow down I/O and not recoverable on retries.

Fill errors (hex): an option to fill data with a 4-byte value when I/O error is reported, to reveal damaged data output.

Jump over sectors after error: skip the given number of sectors when an unrecoverable error is encountered.

If there are areas of sequential bad sectors then skipping significantly reduces loading and further device damaging. Herewith the recovery quality reduces if there are only individual bad sectors.

Read back after jump: read skipped sectors backward after a jump until an I/O error is encountered.

The option is unavailable if the number of sectors to skip is too big. The feature improves the percent of the data succesfully read.

Fill skips (hex): 4-byte value to fill unread data due to skips/jumps.

Additional Parameters

I/O buffer size in sectors: the maximum number of sectors transferred per I/O operation.

Timeout, msec.: time in milliseconds to wait for a device responce (for DOS ATA Interface).

SCSI/ATA Timeout, s.: timeout for IO SCSI/ATA interfaces (Windows, may be ignored by OS).

ATA software reset if busy: perform ATA soft reset if device is busy after a timeout (for DOS ATA interface).

ATA software reset timeout, ms.: time to wait for a device readiness after ATA soft reset.

Script...: set custom Device I/O Handler.

SMART: show SMART report.